Processing power has very little to do with a console's lifespan ... With the exception of the Neo Geo, in every generation to date the consoles with the most processing power have had shorter lifespans than consoles with less processing power; the NES, SNES, Playstation and PS2 are the most recent examples of less powerful consoles having much longer lives than most of their competition.
The PS3 is currently selling at a slower rate to the Gamecube so assume that it has a similar sales rate for the rest of this generation ... In 4 years the PS3 will have no third party support, sell so slowly that retailers want to drop support for it, and no consumers have interest in it anymore; how will it compete with cool new hardware when it has so much going against it?
