If only this were true. Even if they sell a boatload of the 480's it won't stop Nvidia from gouging. Nvidia has built their brand to the point where people will gobble up their products even when they are over-priced and under-perform.
Besides, even if AMD looks to be making a dent in Nvidia's profit margins, there is always the underhanded option available to them of finding out where Polaris/Vega are weakest in performance compared to Pascal and exploit that through Trashworks they have established in most of the AAA titles.
Not even an Nvidia hate post btw, Developing their brand like they have is expensive and difficult to do, was just a smart business decision on their part. Trashworks, while shady, is legal and effective, so again, smart business move.