After 2027's entry take a year off, switch to 4yr dev cycles for IW & Treyarch, staggered by 2yrs with a game releasing every other year. Dump PS4/X1 and completely overhaul the tech so you can really impress people and push both new experiences and significantly better quality of life improvements with ui, ux and game function (no more HDDs or old CPUs).
Have each of them plan out a trilogy over their respective 8yrs effectively covering the next gen into the next next gen. Reinvent/reboot their respective BR-style games to run in parallel to each of them and tie in alongside the mainline multiplayers and the campaigns. Let both choose what they want to do for their franchise trilogies within some reasonable bounds. Again, plan it properly, no more tacking crap on and shoehorning stuff together in half-arsed ways.
Get rid of forced bundles and rotating storefronts. Make every add-on mtx item available individually, all the time and at a lower, reasonable price so people can pick and choose what they like without a high barrier of entry and being forced to buy giant bundles for that one thing they like. Bundles can be discount opportunities or a means of curation. Provide plenty of base content too of course...
By way of not alienating so many people you may actually get more engagement and make more in the end. With people taking the time to actually make new assets. I'd be happy to throw an extra 50 quid their way over the course of the game's first year for extra skins and weapon blueprints etc. if I'm really into the game, but only for stuff I really want. I'm not giving them a penny if I just get two bundles for that and a bunch of crap I don't want with the mere two or so items I do. Just stop the predatory crap, it's counter-productive in the long run. Meet people halfway and you'll find a lot more people; and they'll keep turning up.
Have RTGI + reflections as standard to reduce bake data and allow for fully dynamic multiplayer and BR maps with changing times of day and lights that can be shot out (plus things like enemies visible round corners in reflections); NVGs could also be employed in certain situations in this context. Have everything just be completely fluid.
Completely redo the UI/UX, the last few games have been trash. It's time for something super-slick, responsive, well-organised, nice to look at and with real depth, also needs some iconic, atmospheric sfx and music. It needs to be a pleasure to spend time in and navigate.