That's probably not a done deal. I think they'll use the unit best suited for the system they are building.
The only reason not to use ATI/AMD would be if the integration with intel chipsets is severely compromised. Personally I prefer ATI to Nvidia.
I heard that intel was going to be spending crap loads more money on graphics development the next couple of years. Looks like there isn't going to be an automatic intel/nvidia marriage just cuz AMD bought ATI.