PPC is far from dead.
Mind you, the Cell processor of the PS3 is PPC based, (as well as the processor of the Xbox 360, which is essentially a slimmed down Cell processor).
And AFAIK a new Cell processor has been released very recently.
PPC as a desktop CPU is dead and buried. Who is left producing the Cell, Toshiba? You have IBM pushing the Power CPU, but that's not a desktop CPU. Freescale has changed it's focus to ARM, and I don't see any future for the AI/Hyperion nor MOS to remain in a dead Arch where they have to live off of used EOL machines or machines they are locked out of. Can you?