A Tech look behind the incredible Matrix UE5 Experience
www.fxguide.com
"The final experience however is indicative of what is possible for a game, running on a PS5 or XBox Series X/S there is still a lot of CPU headroom that would allow a game designer to run the normal mechanics of a game. The team did not want to build a demo that was unrealistic for what a new AAA game would be able to achieve."
So it's possible to have full games like this, it will be very interesting to see who will accomplish this for first....