Isn't the Xbox 360S powered by a semi-APU consisting of the ATI Xenos and IBM Xenon?
If so, wouldn't it be possible for Microsoft to include a IBM/(ATI) APU in the NextBox? I kinda hope so, IBM and ATI/AMD have worked very well for them this gen, it'd be just silly to switch.
Might be completeltly wrong here and remembering shit that doesn't exist.
Edit: Hmm, not sure whether the XCGPU qualifies as an APU?