AMD and Intel would be HAPPY to replace them, and plenty capable.

Game consoles like PS5 have been AMD for a few generations. Steamdeck/Steam Machine are AMD.

But really, Nvidia has no reason to leave gaming behind. They can just start dialing back their ambition on the gaming side and providing GPUs that aren't too useful for inference or training. All gaming needs is stability so that devs can aim for something. Games looked great 20 years ago and they'll look great 20 years from now, as long as developers know what they are building for.