How can you have two separate devices and not have some kind of bus between them?
I can't see a CPU/GPU hybrid as being a viable option for gamers, it would require a brand new architecture to achieve that, and even then i dont think it will be too great - they go about doing their work in 2 totally different ways.
as long as ATI still produce gpus (which im sure they will.. AMD surely wouldnt neglect that aspect of ATI) i dont see how Nvidia will just suddenly own most of the market from intel or ATI?