After perfecting graphics, the next logical step is interactivity. Yeah, two different games on two different future systems might look similar, but the extra power weilded by system B will allow much more interacticity. Advanced AI, Improved sound, complete freedom to interact with the enviroment, (I.E. Touch, smell, taste, push, pull, break, use, pick up, build, ANYTHING and EVERYTHING in the game enviroment. From the largest building to the smallest weeds growing out of the sidewalk.) That\'s the future of games after graphics.
Not to mention that they\'ll be other graphic interfaces too. VR and other forms of player immersion. Maybe even Holograms.