And if AMD fail and Nvidia is the only option on the market are you going to be happy to stump up the extortionate prices Nvidia is charging? A lose lose situation for the consumer perpetuated by such fanboyism.
Nvidia already prices the high end irrespective of AMD because guess what, AMD aren't competing in the high end right now. Want a 1070 or 1080, well that is the price Nvidia want to charge regardless of AMD's existence.
This kind of scaremongering it is not useful to anyone. Nvidia's sole purpose of existence is to maximize return for shareholders. It would be illegal for the CEO of s company to attempt anything differently. Business 101 is product pricing. Increasing prices reduces sales and there is an optimal point every company tries to reach regardless of competition. Without AMD prices wont change that much at all.
A few things would happen in a world without AMD:
Release schedules would liekly lengthen a little. This gives more time to tune designed and fix issues with new stepping so the final silicon performs better with less failures. that in itself can reduce production costs This will also mean hard launches are the norm, with more advanced drivers. There might even be a shift to increase the architectural changes between each revision, so instead of smaller evolution to make sure there is always a new shiny product every year, there a fewer but bigger steps. This is cheaper long term. Without direct competent there may be more risks in design changes to try to revolutionize technology, instead of making the N+1 changes we are accustomed to.
The PC gaming world would turn very similar to consoles with more stable hardware and a single vendor meaning game devs can better optimize games and things turn more generational. Instead of smaller incremental changes the bigger changes come along.
There is still plenty of competition form Intel though. The low end is where nvidia really has to focus in the future to keep intel at bay. Furthermore, NVidia have huge competition in the compute space. Nvidia are industry leaders here and this is allowing them to expand in to autonomous vehicles and dedicated deep learning farms. But Intel, google and a host of start-ups are all coming out with very powerful solutions. Some of this technology benefits gaming, some doesn't. I also hope n the future deep-learning will be applied to game engines, obviously for character AI but in theory it can be used for making realistic graphics, designing massive and realistic worlds that are too expensive to create by artists etc. Deep-learning is having a massive impact on areas like texture synthesis.
So even without AMD Nvidia still have competition, but they might become more compute focused. High end GPUS might be released less frequently but will be bigger increments with plenty of supply.