I think it's not that games are becoming more realistic, it's just that the range of possibilities for art in games is getting closer to realistic.
There are still many games that have a distinct art style that is not at all realistic (off-hand, Castle Crashers and Braid on XBLA come to mind).
Will we have non-realistic FPS games? Maybe, but unlikely, as one of the points of FPS games is to immerse people in a world, and making that world look as real as possible is part of that goal. Right now, I'm having a hard time thinking of an FPS game that is non-realistic (Madworld on Wii?)
There are still many games that have a distinct art style that is not at all realistic (off-hand, Castle Crashers and Braid on XBLA come to mind).
Will we have non-realistic FPS games? Maybe, but unlikely, as one of the points of FPS games is to immerse people in a world, and making that world look as real as possible is part of that goal. Right now, I'm having a hard time thinking of an FPS game that is non-realistic (Madworld on Wii?)