Nvidia made a poor decision by pulling out of the AMD Chipset Market. It may only be 2x% of the total, but it still gives a Competitor a huge chunk of the Market uncontested by anyone.
That said, I think AMD also made a bad decision by pulling out of the Intel Chipset Market. They could possibly double that side of their Business by sticking with it. However, with Fusion coming and their Integrated Video already being top notch, I think they're expecting to leverage more CPU Sales with their Chipsets. A strategy that might already be working and may work even better next year. Seems clear to me that AMD doesn't even consider Nvidia a competitor in the Chipset Market any more and that their strategy is solely focused on competing with Intel for CPU/Platform Marketshare.