Many people have COD fatigue and while still a huge franchise it isn't what it once was sales wise. Wouldn't skipping a year potentially fix that? Absence makes the heart grow fonder.
This would also potentially get people to purchase some of their other franchises that they might not have before.
The fact that this IP was the best selling last year, I doubt that greatly. COD's dip in sales all the time from each title to title, as in MW reboot sold 30 million units...that doesn't sound like a fucking series that "isn't what it once was", shit you could argue that it isn't what it once was in terms of last gen sales...sure, because COD has sold MORE FUCKING UNITS during the PS4/XONE gen then PS3/360 gen, so I don't see any evidence to support what you are saying and in fact the opposite is happening, the IP gained more popularly.
Stop using 1 game to pretend suddenly something has changed, the games dip in sales based on era or what team is making a COD etc, but I see no fucking evidence that skipping a COD is magically going to do anything, if someone hates WWII, they won't buy that COD, doesn't matter if its this year or next year, if anything it means they'd lose even MORE money cause they just skipped an entry.
So even with Vanguard sales not being 100% MW2019's, none of that matters, it ranked #1 world wide and moved a fuck ton of units for Activision, this while bullshit of telling us that it sold less then the last is irreelvant to MS, trust me when I'm telling you this, the game moving 20 million instead of 30 million doesn't have anyone worried and its silly to really believe the number 1 game last year really has the publisher upset or something, if anything you'll just see them try to replace that 1 team thats making those low selling COD's for another team, but the yearly release I don't really see it in jeopardy.
Also dear god stop with this insulting shit like "get people to purchase some of their other franchises" why the fuck did they buy Acitivsion if they didn't want COD sales? Ohhhhh so stop making a IP, to sell another IP, ummmm why did you buy this publisher if you didn't want to sell its IP? A market exist for Doom, Halo, Call Of duty etc, they can buy what the want and you can't fucking force them to buy "other franchises" , it makes it sound like people just buy games by default and you can just cattle them in to buying Peppa Pig FPS or some shit just cause some IP isn't coming out that year, that doesn't mean that install base will buy ANYTHING, i see no evidence of that.
Spread out the releases and put them all out, if a market existed to buy them all before, they still exist to buy them all now.
I don't see how it being 1 publisher now suddenly changes that.