It's actually already happening. People don't even look at the actual graphics anymore, the reasoning behind getting something relies on pointless numbers that they don't even understand most of the time - CPU, GPU, FPS, resolution, etc.
The people who buy a console or game because of graphics today will still buy them for graphics in 20 years.
Still, I don't think we're anywhere near truly real graphics. Sure, there are some very good-looking games out there and stuff like The Last of Us and Uncharted do look pretty real when it comes to models and lightning... but they just don't look real. I think there's still a lot of room for improvement, especially with animations.