If Amazon puts all their resources behind this new buying policy, and they should. It is possible to wound the auction giant E-bay; however, they too have plenty of resources to compete. Furthermore, what it is all going to come down to is innovation and evolution. Both companies are going to have to do both those things, not just because of each other, but because Amazon or E-bay does not just want to go out by their own hands either.
No.E-bay's bidding format is still a way for individuals to sell their own products in a guaranteed fashion that tends to be priced at reasonable levels. In comparison, Amazon's listed marketplace prices does not involve a guaranteed sale. Additionally, it is easier to search for bargains on Ebay due to the available search tools than compared to Amazon. Also, Ebay is available internationally, while Amazon is limited.
I do not believe Amazon's one-on-one price negotiating will have an impact on E-bay auction listings. The two sites are separate and for the most part have different consumers. I think Amazon's site is clunky and difficult to navigate. It has become too hard to navigate their products and that will hurt them more than help them, regardless of their price negotiations.
Amazon have been wanting to compete with E-bay for a long time and it gives sellers and buyers more options. E-bay ratings are genuine and can't be bought, where Amazon ones can be bought, so E-bay sellers and buyers are still seen as more reputable and trustworthy which is what people look for. People are more concerned with a good E-bay rating and keeping it as it can make or break sales.