They've spent the last decade covering up negatives attributed to active players and total unit sales and as they've got this down to a tee, I can't see them needing to do it again. I reckon they (Microsoft) are simply willing to take a monumental financial hit at launch in a bid to prop up game pass figures and then bleed what players are left even harder down the line to recoup any lost revenue. No matter how many more sign up to the pass just for this game, it wouldn't come anywhere close to had those prospective players bought it outright. They can also play the 'we have 25m players' card even thought they just count people who try the game once and aren't considered active players.
I can see it going the same way as Starfield especially in terms in it failing to grow the pass and instead having existing pass holders getting a free ride. Bethesda thought they could get 100m users on board across 1bn devices and in the end they got about 10m players and new game pass subscriptions practically flatlined. Microsoft will need about 220m game pass subscribers every time they plug an in-house AAA title yet I don't think they've reached 40m yet and like the Epic Game Store, it ain't growing.
Black Ops 6 is more a Gulf War game so it may have more modern elements and there's rumoured to be a mission surrounding 9/11 so the early 90's to 00's could very well be the setting.