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btw, what comes after next-gen? Think about it! The whole "thing" is, actually, stupid.



When the next generation is annoucned or after some time has passed, the former next generation becomes the current generation. It's that easy.

Consoles allow talking of "generations" (while I think this is not so easy with game engines - different topic).

Usually all 4 or 5 years (lifespan tends to recude more and more with each new generation) a new clearly defined (hardware upgrades are the exception, the console package usually is fixed pretty much and stays like this for the lifespan) generation is introduced, so there is a somewhat clear pattern.
Saying this, I don't count redesigns (DS Lite) or feature slimming (PS3) a new generation.