"True" photorealism is years away, especially in character work. It's not just a matter of getting a photoscan rig, and facial capture. The shaders have to be created to properly mimic the way human skin looks, then we have to capture the movement correctly, not just the expressions of an actor wearing a face capture rig.
All those minute muscle fluctuations and flutters of an eyelid...a twitch of a nose. These are the things that characters are missing, and what throw the realism out. No matter how sophisticated the capture tools are now, we still are not quite there.
Not true, I as a CGI artist have created photoreal pieces - true photorealism also - is something seen across swathes of Unreal Engine Student Reel's. To accomplish photorealism now, today - all you need is a team dedicated to delivering photorealism opposed to a team delivering a game that can be incrementally improved graphically with every new iteration.
Here is 1 not even good example of what can be accomplished with photorealism now -
Full Immersion Based Photorealism is also just within reach, if you look at recent examples in character work all that was needed were nuanced spec map's and this one improvement - a technique developer's have been excluding for about the last 7 years - catalyzes a new level character depth not seen before in gaming. Senua from Hellblade 2 is arguable something that the Series X should be able to accomplish in real time. And while it is not a perfect example of photorealism (really this fall's into the category of Full Immersion Based Photo Realism - with less break's in immersion due to character animations) it is far superior to what has been seen in the past.
As far as purely delivering a game that is photorealistic - we just don't have team's dedicated to delivering a photorealistic experience working on next gen titles. You could have stunted - unanimated faces but deliver them in a photorealistic manner today while striving to maintain photorealism and it would look leagues better than anything seen before. A modest game boasting photorealism could already be in gamer's hand's - it's a pity there hasn't been one.
But there are literally 100's of nearly flawless examples of photorealism now - I as a CGI artist's have tested this barrier and I know first hand that If I aimed to deliver a photoreal walkthrough that looked better than what is shown - it isn't terribly difficult.
Do these examples offer break's in immersion? Yes but immersion is not photorealism
Immersion Based Photorealism - or Photorealism with the caveat of a flawless camera and flawless animation's - an experience that does not break
immersion for the user - is something a team with 100% certainty could begin working on and deliver fairly soon if those people intended to.
Marbles -
Arguably the first Photorealistic "Game"
Photoreal Unreal Engine Tech Demo's
Arguably Photorealistic - Break's in immersion surface due to First Person Camera Constraint's
This does not render the below less Photoreal.
It does mean a Photoreal Game (even Modest) with few break's in Immersion is the foundation team's should build on.