i don't know why we're even having this conversation. Regular Xbox just used intel chips. I don't see why they can't just use Intel Chips again (or even AMD). And why does it always have to be custom made anyways?
They could just pop a standard burly intel Quadi or Octo core chip in there (whatever MS prefers) and go. Consoles are essentially computers anyways.
And since developers are used to programming with DirectX and Intel architecture, then dev time should be pretty quick for Xbox720 games.
Essentially the next gen console should look a lot like a Mac Mini with a TV connector and some proprietary controllers. Put a piracy lock on that sucker and release it out to the public!
Graphics and Computer horsepower is so cheap and commoditized now-- it makes no sense to make custom chips when any old thing will do.
