I'm not too sure about nVidia losing out in the notebook market...
AMD's fusion/platform may lock nVidia out on the AMD side... but the Intel side is larger, and I don't really see Intel delivering high-end solutions yet, so they need nVidia (and/or AMD) for that market.
Then there's Tegra, as mentioned...
And Fermi... could be turned into a success story with the next die-shrink and/or refresh.
Ofcourse Fermi also has a GPGPU-side to it, where I think it really has no competition from AMD, partly because Fermi has incredibly strong performance, especially in double-precision arithmetic, but also because nVidia has a more mature development environment, with Cuda/OpenCL.
Another area where nVidia may have good chances is when the next generation of consoles is coming up, which should probably not be more than 2-3 years away.
So we'll have to see... As mentioned above, nVidia has been profitable so far, so there is still plenty of time to fine-tune their product line and design a new strategy for the coming years, if need be.
Perhaps nVidia will not be the same company as we know it today, but I don't see them disappearing anytime soon.
What Nvidia doesn't have is plenty of time. There's a reason JHH tried to shoehorn a brand new and massive architecture into a brand new fabication node. While at the time he made that decision he was doubtless considering Larrabee a much larger and closer threat to his gpgpu plans than it turned out to be, there was also Fusion on the horizon, which he knew he had no answer for in the OEM notebook and desktop market. Intel and AMD CONTROL the 86 market and he knew it was only a matter of time before he was shut out of all but the discrete gpu market. Which is exactly what is happening. In reality, it is Fusion that is also going to be the biggest near term threat those gpgpu plans.
Markets can turn sour VERY fast when you become price uncompetitive. Look at Nvidia's discrete graphics market position change in just two years. If Fusion is successful in the notebook market, providing performance at a price Intel/Nvidia can't match, that market can turn sour for nvidia in a year because THEIR OEM market is in higher end notebooks that need better than Intel graphics. Similar scene with the cutthroat entry level and mainstream desktop markets where Fusion's price/performance advantage can make a big enough difference that AMD could grab substantial market share in a years time.
That CUDA edge Nvidia has can dissappear pretty quick if Nvidia starts having severe cash flow problems and has to start laying people off and AMD starts (or likely already is) putting substantial resources into and focus on developing open cl and open gl etal in preparation for Fusion's release. With AMD having stated Fusion IS their future path, it would be unlikely they are still neglecting developing the programming end of the plan.
Why would Nvidia fare any better with consoles. The same advantages Fusion brings to mobile and desktop applications, it would also bring to consoles, and being able to tailor a gpu/cpu mix to match a particular console specification.
The major publishers are undoubtably pressing for next generation consoles that are far easier to port to and from. If so, that doesn't favor Nvidia.
Then there's Apple taking a close look at Fusion. That could be a major hurt for Nvidia.
Fusion is just an incredibly potent computing solution. AMD has to be able to execute on it, but the track record there has been pretty stellar of late.
Nvidia AND Intel will be hard challenged by it.