Why do we need next gen for HD graphics and 60fps? Plenty of games do that now.
On the graphics front getting not only 720p or 1080p at higher framerates, but also a lot better texture filtering and anti-aliasing across all fronts. More memory for more detailed geometry, textures (+ additional layers like higher quality normals, displacement maps, etc), and bigger / seamless worlds. If next gen adds real 3D grass, interactive water, leaves, etc as pretty standard with richer particle systems and post processing + IQ improvements (a lot of that is low hanging fruit as PC versions have this stuff) graphically the image quality can take a big jump.
Improvements in processing power to handle richer AI, physics, motion processing, persistant worlds, etc
Every generation needs a hook. This gen HD and motion controls were a hook (first games were just incrimental last gen titles and a lot of the best games are evolutionary) but the coming gen may see 3D displays (120Hz so GPUs outputting 2x60fps), advanced motion controls and cameras, etc as a hook. Digital Distribution, a toe into cloud gaming, etc. But for "standard" games to get the bleeding edge adapters excited offering a big jump in IQ (think Crysis+ at 60fps) won't hurt. Even the FM3 photomode shots could be matched or outdone on newer hardware, which would be a selling point to many.
Motion Control 2.0 + Online Networks 3.0 + Cutting Edge Hardware + Killer Software above this generation + whatever hook (3D displays? VR?) I am sure will get the ball rolling. But we are what, 3 years away still?