The PS3 and Xbox360 won't go away in the next 5 years. The issue is not so much PPC (which should get support anyway), but various other silly things, like needing to rely on certain interactions between the compiler and runtime library. This is not a huge issue, but any extra bump will deter people from trying.

And indeed it's possible to have an alternate toolchain, but lots of work that is best avoided most of the time.