I think that Rainbow Six: Extraction has proven a bit of a point.
Siege players actually want to play a PvE experience with the characters we know and love.
So why not do that again, but in a more canon fashion?

I propose a new tie-in game for Tom Clancy's Rainbow Six: Siege, one which expands off of the engine, operators, and arsenal in a cooperative PvE experience as Team Rainbow takes the fight to the White Mask terror group. I introduce to you :

Tom Clancy's Rainbow Six

------ OPERATION // SHATTERED MASK ------

Simply put, this would be another tie-in game that is developed by a separate team.
While Team A still focuses on developing extra content for Rainbow Six: Siege, Team B expands on the design of Siege to make a highly-replayable story experience that very much copies the gameplay of Siege's sandbox of weapons, attachments, equipment, and operators.

TCR6: OPERATION // SHATTERED MASK would feature a few gameplay modes, all of which focused on the White Mask organization.
Story Mode focuses on, well, the story itself by starting off where we left off with Bartlett University.
Besiege Mode focuses on Terrorist Hunt operations from the Attacker's perspective.
Holdout Mode focuses on Terrorist Hunt operations from the Defender's perspective.
Firing Range is simply just a firing range mode where-in players get used to the operators and the wider array of weapons that players can utilize.

What makes each game-mode stand out from the rest is how Attackers and Defenders... don't really exist in TCR6: OSM.
Sure, you still have the operators that we know and cherish from Siege's Attack and Defense teams, BUT they are not just relegated to one side of the battle.
Each mission allows players to pick and play as ANY of the Operators in Team Rainbow, squadding up with a team of up to five players to work cooperatively, with each Operator getting a chance to have a highlight in the mission.
The enemy are gathering to make a push towards the squad? Operators such as KAPKAN and JAGER get some time to set up defenses in the local structure to better increase the mission success.
The White Masks have fortified a location in your path towards the main objective? Operators such as THERMITE and BUCK are now on-point to ensure the team has an entry-point into the fortified area.

To add on-top of that, unlike in R6: Siege where you have to balance the game for PvP encounters and ensure that operators are not over-powered to frustrate rival players too much, R6: OSM is not so restricted.
Thus, not only can your squad have both Attackers and Defenders on your team, BUT you can also have any weapons in the game equipped... within reason of course.
For example, SLEDGE in vanilla R6: Siege makes use of an Assault Rifle, a Shotgun, a Pistol, and/or a Machine Pistol.
Ergo if a player wants to squad-up as SLEDGE for a mission, they can pick from ANY of the weapons that fit in these four categories.
And they can also equip whatever attachments they want for their firearms.
For example, the SPSMG9 from Siege has lost its Muzzle Brake attachment in Update 4.1.0 of Siege. But since PvP balance is not an issue to consider, the Muzzle Brake is returned for the SPSMG9 for use in the PvE modes offered by my proposed game of OPERATION // SHATTERED MASK.
The only restrictions to arsenal are what weapon classes the Operators are set to use and if their Unique Utility Gadget is part of their arsenal and causes some restrictions, such as NOMAD and BUCK not being able to utilize foregrips due to their gadget being under-barrel or MONTAGNE, BLITZ, FUZE, and CLASH having to make use of their Riot Shields as their Primary Weapons Slot.
And when it comes to standard equipment (Frags, Nitro-Cells, Stuns, Claymores, Breaching Charges, etc.) players can pick whatever gadgets they want regardless of which Operator they are picking. Should KAPKAN have access to Claymores? Why not? Be dastardly with your strategies!

By allowing players to both play as Attackers and Defenders of their choosing and to equip whatever weapons and gadgets they desire, it invites maximum replayability for each and every single mission and game-mode.
Playing Mission Three again with a full squad of buddies?
It's not going to play out anywhere close to the same when it comes to the firefights you encounter and the strategies you employ, all because of what characters and tools you bring to the excursion and how the White Masks arrange and fortify their locations. Just like with T-Hunt, they might have Nitro-Cells scattered in a certain location or they might have fortified a random room with deployable barricades and reinforced the walls.

"But what if I don't have a full squad of buddies?" I hear you asking.
"What if my friends are not online and I don't want to play with a bunch of randos that can be griefers?" You worry.

Well, worry not. You can still play the game solo!
No, I do not mean you are entering the missions as a lone-wolf, though that is still entirely an option as a difficulty modifier on the story mode as it GREATLY restricts your character's capabilities and bumps up the challenge.
BUT you can play alone with up to four A.I. team-mates that will follow close behind the player.
Utilizing the ping system and a new voice-command system, you will play the role of squadron leader and coordinate your A.I. teammates, bringing to mind the gameplay execution from Rainbow Six:Vegas/Vegas 2.
"THERMITE, place your Exo-Thermic Charge here," you command as you ping the fortified wall, "MONTAGNE, get up front and extend your shield. I.Q., stack up behind MONTY and scan for electronics. ALIBI, I want you to place a decoy here(*ping's floor nearby) and then take up position here (*pings a location behind a car with an angle to the breach point.). On my mark, THERMITE blows the wall...three...two...one...MARK!"
*Thermite blows the wall open, enemy fire shooting towards Monty as the WM enemies target the big guy and reveal their locations by shooting ALIBI's Prisma. Player tosses a flash-bang into the room.
"MONTY, I.Q., push forward to the opening."
*Monty and I.Q. stay in line and push forwards, I.Q. shooting at targets as her A.I. gets the chance to get a clear shot if she can while staying stacked-up behind Montagne.

That is how I envision the single-player squad-leader options to be.
Slower gameplay?
Sure, you have to plan methodically and give voice commands with pings to get your team in position and ready to push in.
But I would argue that would be part of the beauty of the single-player experience, harkening back to the old-days of Rainbow Six where you had to plan methodically and give commands to your squads to execute. Only now it is a bit more in the action and adds a bit of realism to how a CTU squad would move and operate in the field.
You of course would not have to do this when playing co-operatively with 3-to-5 players or when playing in the extra-difficult Lone Wolf mode.
Honestly, if you are playing Lone Wolf; it might be the prime style of play that would allow RECRUIT to outshine the other operators, as RECRUIT would be the only operator capable of wielding every weapon in the entire game.

Now.
I do understand that the modern Rainbow Six audience is mostly focused on the multiplayer aspect of the game.
So... how could one boost sales of this Rainbow Six title?
A couple of ways actually.

The dev team for TCR6: OSM would have some of the map designers hyper-focus on key areas of the map.
For example, let's say in Mission Four you have the finale taking place in a Private Estate for an HVT that is being secured by Team Rainbow, an individual that the White Masks seek to keep silent.
This Private Estate is designed to be a full-fledged multiplayer map ideal for both PvE and PvP experiences, as the map designers work alongside testers and map designers with Team A to ensure the map is well balanced and plays well.
Why do this?
Well, with the launch of TCR6: OSM there will be an update that would add in SIX new multiplayer maps that are locales featured in the story mode of OPERATION // SHATTERED MASK !
Players don't have to buy the PvE story game to gain access to these maps, being a free update.

What players do gain access to when they purchase and play OPERATION // SHATTERED MASK is a set of ten new operator that are made available for unlock in Rainbow Six: Siege by playing through the story.
Five new Attackers
Five new Defenders
Most of them will come in as reinforcements for the Pathfinder CTU teams, while two of them will be new operators added in from new CTUs.
The reason why two of them are not from the Pathfinder CTU teams is because of FINKA and LION, both of which hail from the Spetsnaz and G.I.G.N. respectively. Ergo, those CTUs have five units while the other Pathfinder CTUs only have four currently.
I already have designs for these ten Operators so I will link my documents on these ten proposed operators.

UK SAS - SHATTER (Attacker)

https://docs.google.com/document/d/1KUXgCl73XzInI2qkpjCv1Qmy2heJw8Wy-7v01qYXCfk/edit?usp=sharing: (https://docs.google.com/document/d/1KUXgCl73XzInI2qkpjCv1Qmy2heJw8Wy-7v01qYXCfk/edit?usp=sharing)

UK SAS/CBRN Threat Unit/REACT - CACHE (Defender)

https://docs.google.com/document/d/1kxUi7xccuHcgFLtaYm05gKGxbo3TXGHfWRoWddMgPkg/edit?usp=sharing: (https://docs.google.com/document/d/1kxUi7xccuHcgFLtaYm05gKGxbo3TXGHfWRoWddMgPkg/edit?usp=sharing)

USA FBI SWAT - DECOY (Attacker)

https://docs.google.com/document/d/1UrcngB2AKb1ddu_7pKBGHnQ08cGsvWj6CXVFzPqvrHM/edit?usp=sharing: (https://docs.google.com/document/d/1UrcngB2AKb1ddu_7pKBGHnQ08cGsvWj6CXVFzPqvrHM/edit?usp=sharing)

USA FBI SWAT - VOID (Defender)

https://docs.google.com/document/d/1sMKygq4EFDkupl2RK4ANLEbpSHDQmkERBIICQlUtVK4/edit?usp=sharing: (https://docs.google.com/document/d/1sMKygq4EFDkupl2RK4ANLEbpSHDQmkERBIICQlUtVK4/edit?usp=sharing)

Switzerland ARD10 - LAZARUS (Attacker)

https://docs.google.com/document/d/1Px2OpgUV215Sja-1MSqnTfNjiy7-aoH2nOMW1oKpgOs/edit?usp=sharing: (https://docs.google.com/document/d/1Px2OpgUV215Sja-1MSqnTfNjiy7-aoH2nOMW1oKpgOs/edit?usp=sharing)

France GIGN - GAULOIS (Defender)

https://docs.google.com/document/d/1-kgsE6dsjzOHhcoXp8vCX5Eb3Fy7m4g1CU6iEuIwpA4/edit?usp=sharing: (https://docs.google.com/document/d/1-kgsE6dsjzOHhcoXp8vCX5Eb3Fy7m4g1CU6iEuIwpA4/edit?usp=sharing)

Israel-Palestine IDF - ROGUE (Attacker)

https://docs.google.com/document/d/1WBKuA9ZZXZ9nD2De7LtvI32vfxKI_udbFFttAxwZTvQ/edit?usp=sharing: (https://docs.google.com/document/d/1WBKuA9ZZXZ9nD2De7LtvI32vfxKI_udbFFttAxwZTvQ/edit?usp=sharing)

Russia Spetsnaz/Bodark - ZVEZDA (Defender)

https://docs.google.com/document/d/1PdoRzRwVhGNHPcz0o4ynR1mL2uYC0j-Rs7CgPDyObM4/edit?usp=sharing: (https://docs.google.com/document/d/1PdoRzRwVhGNHPcz0o4ynR1mL2uYC0j-Rs7CgPDyObM4/edit?usp=sharing)

Germany GSG9 - RAPTOR (Attacker)

https://docs.google.com/document/d/1G7uK52xjBZmGiMQwAsysTuBo7HwMjPiambz5nP2y--8/edit?usp=sharing: (https://docs.google.com/document/d/1G7uK52xjBZmGiMQwAsysTuBo7HwMjPiambz5nP2y--8/edit?usp=sharing)

Germany GSG9/CBRN Threat Unit/REACT - GLARE (Defender)

https://docs.google.com/document/d/131e5fZjiQbvsls9OgeczqBe_FyE94lKLeV962oPtqY8/edit?usp=sharing: (https://docs.google.com/document/d/131e5fZjiQbvsls9OgeczqBe_FyE94lKLeV962oPtqY8/edit?usp=sharing)


To so suddenly include ten new operators into Siege as a bonus reward for playing the hypothetical OPERATION // SHATTERED MASK could be argued as ludicrous.
Hence why I would recommend EXTENSIVE game testing to ensure that the characters are balanced at launch.
But I do believe that this alone would be a very enticing prospect for players to buy in on the PvE game. After all, not all fans want a PvE experience.
But by doing a single playthrough of the main story, Siege players will unlock five new Attackers and Defenders for use in Siege itself.
Considering how much a single Battle Pass rewards an Operator at a certain cost of cash, getting ten at once for the price of a single game would be one helluva bargain.
Add on top other cross-play unlockables such as skins, headgears, uniforms, Elite Skins, Weapon Charms, and you have yourself all the more enticing.

And then there is the post-launch content.

Does anyone remember Rainbow Six: Patriots?
Why not reignite that storyline and have it tie-into the story of the White Masks, the Patriots event being a domino effect for the opening of the White Masks organization to rise up? The twist being that ex Rainbow Six operators are the kingpins of the White Mask organization, the secret goal of the White Masks being to show the world what the result of shutting down Team Rainbow after the events of The Patriots. After all, an international CTU was a shield raised for a reason. Just because the shield is broken doesn't mean you drop it and don't replace it. Without replacing the shield, you are only willingly exposing yourself to whatever attacks of opportunity your opponents wish to make use of. What is a world without a rainbow? The White Masks symbolize how a threat can come from anywhere, across any borders, and a world without Rainbow is a blank canvas filled with threats around every corner.

Thus, we will have a DLC Story to tell as well, in the form of an interrogation of the ex-Rainbow members that are the heads of the White Masks :

OPERATION // ARCHANGEL

And there you have it.
My idea on how a Rainbow Six Siege story-driven PvE cooperative game experience could be executed effectively and how to beautifully weave it together with R6: Siege.

Thoughts anyone?
Hire me Ubisoft?

@RamboBambiBambo There is a problem: if I'm recalling correctly operation Archangel was an operation in the Ghost Recon game series, which was a cross over for Rainbow Six Siege where Caviera went to Bolivia secretly to help her brother. After not hearing from her for a while the Rainbow team sent Valkyrie and Twitch to Bolivia to find her with the help of the Ghosts. You will need to find another name for your operation.

@Justifier-98
So it is, my mistake.
I was referring to the events of Tom Clancy's Rainbow Six: Patriots, and in GR Wildlands, Nomad brings up a failed operation. I was under the impression they said OPERATION // ARCHANGEL, but it was actually OPERATION // PATRIOTS that Nomad said. Here is the dialogue from GR Wildlands that I was referencing and improperly recalling the name of -