For some reason, even with the polygon count getting higher and higher, the shaders and lighting improving more than ever, I don't see video games achieving photo-realism any time soon.
I don't even think it has to do with tech advancing. Seems to me it is a matter of choosing a more true-to-life color palette. The real world is not as colorful as games present it. At best today's games look like CGI-material.
The original Metal Gear Solid for PlayStation with it's infinite shades of grey or the original F.E.A.R. did a lot of things right in this respect imho.