I totally agree that this generation has peaked.
I think the only reason no company has announced the next generation is because the Wii is still making tons of money, and MS and Sony are finally starting to get some returns on their losses (although neither will probably make back what they invested).
Since Nintendo is the only company that can really afford to move on, I think they will do so just to get a headstart on their competition. I think it's almost certain that it would be HD, and that it would be compatible with the Wii (so they could build on the current install base). I expect Nintendo to release their next console in the fall of 2011.
I think Natal and Move will flop. Well, maybe not flop, but not do as well as MS / Sony were hoping. I expect Natal to do better than Move because it should be cheaper and because MS will spend much more on marketing. I expect MS and Sony to release their next consoles in the fall of 2012.
I don't expect any new console to launch with a price higher than $399 (hopefully Sony have learned their lesson).
I expect Sony to launch the PSP2 shortly after Nintendo releases the 3DS. Actually I originally expected Sony to release it before the 3DS, but since there have been no leaks to suggest that, I changed my prediction.