Rendering is not the problem. I would say that the uncanny valley has already been passed for static images rendered in real time by current 3D hardware (this NVIDIA demo from 2007 gets pretty close). The challenge for video games to cross the uncanny valley is now mostly in the realm of animation. Video game cutscenes rendered in real time will probably cross the uncanny valley with precanned animations in the next console generation but doing so for procedural animations is very much an unsolved problem.
(I'm a graphics programmer in the video games industry so I'm fairly familiar with the current state of the art).
I wasn't even considering the possibility of static images in video games, because static images aren't generally considered to count in modern video games. The world doesn't want another Myst game, and I can only imagine one other instance in a game where photorealistic, non-uncanny static images constitute the bulk of the gameplay: some sort of a dialog tree / disguised puzzle game where one or more still characters' faces changed in reaction to your dialog choices (i.e. something along the lines of a Japanese-style dating sim).
I would like to propose this as a thread for people to write in their predictions for the next year and the next decade, when practical with probabilities attached. I'll probably make some in the comments.