Q1 2010 = NV desktop discrete = 64.8%
Q2 2010 = NV desktop discrete = 55.2%
Q3 2010 = NV destkop discrete = 58.8%
Q1 2011 (May 2011 data) = NV desktop discrete = 59.4%
But if you look closely at Q1 2010 to Q2 2010, AMD has only increased its desktop GPU shipments from 6.85 million to 6.9 million units. The entire desktop GPU market has collapsed from 19.61 million to 15.5 million units. I can't easily explain what caused the collapse of the desktop GPU market from Q1 2010 to Q2 2010 and why NV's market share fell so much in that Quarter without doing additional research. But you can see that despite AMD launching Cypress in Q3 2009, NV still has a 59% market share in the discrete GPU space and has been gaining since Q2 2010.
Sure they launched late out of the gate, but since they had competitive products, it didn't really hurt the company that much on the desktop GPU space. AMD has been dominating the mobile GPU space though. Even if Fermi launched at the same time as Cypress, I doubt it'd be able to upset AMD's dominance in the mobile segment anyway since Fermi offerings aren't that great in that segment to begin with.
Of course the strong market share has everything to do with Fermi. That's the main product driving their entire range from Q2 2010 to Q1 2011 today - 59% market share in the discrete desktop GPU segment.
You think in the last 10-15 years NV and AMD have launched each new generation 1 month apart? We have witnessed 'spread-out' launches for a decade. It's not unusual for the 2 firms to launch products 1-6 months apart from each other and it isn't the end of the world for either when this happens. How much market share does the $350-500 discrete GPU market command in total?
You think 5 million people who buy desktop GPUs are sitting there and waiting to drop this kind of money on HD7000 series when BF3 launches? AMD would need to launch 10+ graphics cards from $50-500 all at once in September-October timeframe to even make a dent in the marketplace. We don't have any information even on what HD7000 series are going to be launching in the fall (are they going to postpone mid-range or low end to late Q4 2011/Q1 2012? We don't have any info. Even if AMD launches every product line by Q4 2011, this gives NV plenty of time to launch Kepler series in Q1 2012 and still be competitive. As you have seen in recent history, modern GPUs now have a lifecycle of about 15-18 months. Therefore, even if you launch 3 months later, you still have at least 15 months of sales on that architecture.