TBH I think this is massively underselling the core staying power COD has for loads of people. Plenty of gamers out there who are only really buying the same, broad appeal games every year like FIFA & COD. Only now for the same money they'd pay for COD, they can subscribe and get get COD plus all these other games? I think COD is gonna bring a lot of those people and then a big chunk of them will stick around (especially those on PC etc).
Also I think the Season Pass model and COD shop is where the series generates all it's income these days, and that income is funnelling straight to Microsoft now. It's just gonna keep printing money for them, like GTA Online does for Rockstar and all they need to do is keep supporting it.
I agree the landscape has changed and is continuing to change at a weird pace, but as far as COD goes, they're gonna be totally fine and this can only help their Game Pass sitch.