In
A Few Quick Tips for Kindle Authors and Publishers Stephen Windwalker pointed out that Amazon is happy with a "profit" of about $1.25 per ebook. So at $9.99 the "sustainable" list price (even if Amazon stops subsidizing sales) for new releases is $17.49 assuming 50% goes to the publisher.
If you are an independent author using Amazon's DTP you get 35% of list price, which can be $24.99 and Amazon will still sell it for $9.99.
Amazon's subsidizing of ebooks sales is distorting the market. It means that the optimal list price for a new release is the highest that Amazon will sell for $9.99. Which is somewhere between $25 and $30 for major titles. This helps Amazon by pricing all other ebook retailers out of the game. They don't have the profits from the Kindle to help subsidize ebooks.