I agree, withthe "claim" made by the IBM rep. Nintendo took advantage by encorporating the PPC into the GameCube. A lot of the hard work has been done in compilers and optimizations over the life of the GCN. It wouldbe folly to throw all that out the window (The way Microsoft and Sony have done).
It "seems" logical to develop and ship a system in line with the GCN. The same processor and same GPU company definately point to this kind of philosophy.
As far as PPU, sure if youre going into a store to buy one PPU it's gonna cost you $250. But lets not forget, this is Nintendo here, bulk buying is possible, and seeing as how the console is expected to last for 4-6 years, it would be a worthy investment now(if its actually as great as they say it is). Having a humbler CPU would also leave the possibility of a PPU open imo. Seeing as how game programming is linear as opposed to parallel(from what ive heard), having a single core CPU would not only make it cheaper, but also easier to program.