Call of Duty 'Saturn' is taking place in the near future (2025–2035) and would be including a new villain in a sequel to the Black Ops 2. On custom editor, it's far from done and yes, it will have round-based Zombies mode. The game is a continuation to Black Ops 6 in gameplay designing and follows that road, you'd expect open-world campaign missions, vehicles, aerial fighting and the game would introduces bigger maps than MWIII and BO6 while modern and futuristic weapons are also there.
For Xbox, it will be at least in 2026 and likely cloud-based rather than hardware – in case of handheld console – and reportedly is releasing
with CoD 2026.
On the Battlefield, Tom knows better than me but a free-to-play Battle Royal mode is in the development for beside massive maps to play in akin to Battlefield 2042.