They overdid the WWII genre.... like crazy and COD was a bit late to the WWII party.
Have they made a new WWII FPS lately? Lol that market.... like a dead horse man.
I'm not saying you're wrong about WWII being a dead horse, but the "modern/futuristic" genre isn't a dead horse? That stuff has been stale since MW3. And ever since Black Ops 2 went futuristic it has gotten beyond stale.
The WWII market got old after a while because what more could they do with it at that time? Consoles couldn't produce anything better than what was out. Now that there are a new gen of consoles, why not go back to that era and produce more great games? There are plenty of timelines and locations that they haven't visited yet from the WWII era, Korean War era, and Vietnam era. And if someone is brave enough, the WWI era.
We don't needs drones, robots, and superhuman powers in every shooter. Go back to your roots COD.