Why worry? There are lots of different retailers for ebook.
Direct Selling from authors
Do you think that these companies would stop selling ebooks? Is 30% commission essential for their ebookstore?
This is rather unrealistic. Its like sayting that the market in Office Software is competitive because there are all these competitors to Microsoft Office. "Why there's Star Office, Abiword, Open Office, Iworks, Free Office-to say nothing of the Linux distros and don't forget Word Perfect." In reality, of course, MS Office has 90% of the market and is a monopoly in all but name.
In the ebook market, Amazon has at least a 55 % ( down from 90%) share, BN about 25%, Apple 10%, and then there's Kobo, Sony and Google in single figures and a handful of midgets in the fractions.THAT'S the reality of the ebook market. It's even worse than that, because BN is in real danger of going belly-up like Borders and may not survive a price war with Amazon.
Most analysts think its a question of when, not if, Amazon regains an 80% share of the ebook market under a "wholesale" price model market.