I think the "next generation" of game consoles will likely not do anything revolutionary, the way the PS3 was a huge technical leap over the PS2. They'll probably take what they have now and just make it bigger and faster. Faster CPU, more RAM, more disk space, better GPU.
Honestly, I don't understand why Sony took the approach they did for the PS3. Sure, it was better than anything else out there when it was launched--but by the time most people could afford it, it had already been eclipsed by commodity PC specs.
Even so, I don't expect Sony and Microsoft to come out with new consoles for a couple more years yet.