I would've preferred it to be a DLC ontop of MW2 due to how solid this last game has been. But businesses need to make money and I think they struggle to understand how to make a regular incremental expanding game in the CoD experience. I think their work on Warzone, to DMZ to Raids has actually been a really good progression but doesn't see much positive news because it has an opposite player base to something like Destiny, which is mostly PvE. CoD has far more PvP players so we have to remember that with PvP games it is very hard to add regular content that could make it really enticing to keep on it. Having said that, give PvP players a game which feels balanced, fun and lots of gun/gamemodes to play and they'll just play it for eternity.
Give it 4-5 years we may see the CoD ecosystem move towards the base F2P as it is now, enhance it, and then these additional campaigns with some PvP wrapped up in it become seasonal paid upgrades.