Instead of fabbing out chips from TSMC, Chartered, etc., ATI will have an access to much more advanced manufacturing technology. AMD wouldn't have capacity? I doubt the high-end graphics chips sales are anywhere near the volume of CPU sales. AMD can just share a fraction of fab space with ATI's high-end chips and could still get by with it. Especially once Fab36 runs in full force.
AMD will have capacity once their new 300mm FAB comes online. Right now afaik AMD is supply constrained and with Dell coming into the picture, it wont get better.
This means, when NV'd be designing chips w/ 90nm or 80nm, ATI would have 65nm for their designs. When TSMC finally catched up with AMD/Intel's current manufacturing (say, 65nm), ATI would be one step ahead with AMD (say, 45nm). Mid-to-low level GPUs can still be outsourced from any of those fabbing houses.
process technology seems to play a lesser role in the GPU world than in the CPU world. I think this is primarily due to the design of the transistors in the GPU. afaik they use bulk design transistors and don't do a lot of customization. Plus the product cycles are a % shorter than the CPU world. AMD and Intel debut a new arch and it lasts 4-5 years with specific goals for each process stepping. ATI and Nvidia debut a new arch with performance goals for the next 6-12 months. Either they hit it or they dont and design the next one to top the competititon. If AMD pours millions into customizing a GPU and tweak the hell out of it for a specific goal. Chances are by the time they did so, Nvidia would release a new GPU with twice the resources and smoke it.
This would put a tremendous pressure on NV and would eventually force NV to build its own fabs. (which would take lots of money and time) In the meantime, this would give ATI a great chance to gain its marketshare.
I dont think so, ATI and Nvidia compete pretty decent in the integrated markets against Intel, who has much more fab capacity than AMD. Nvidia will continue to utilize 3rd party fab partners, and may even get better deals due to a lack of demand from ATI.