That's awesome, but what scares me is the long term. If Amazon drives B&N under they get to play in monopoly land, change the terms however they like, and authors have to take it.
I totally understand this fear, but it's not how it usually works. In order to maintain market dominance, most large companies in the past have done everything in their power to keep prices low for customers while treating suppliers fairly. If they were to raise prices and lower royalties, a competitor will spring up overnight to absorb the demand. This is more true in the Internet age than ever before.
Besides, the argument would be thus: I should give up thousands of dollars a month *right now* in order to prevent the unlikely outcome where I *might* lose several hundred dollars a month in the distant, hypothetical future? I'm not going to make that decision.
Amazon has basically given me a career, one I've dreamed about since I was a wee lad. Now they want to pay me handsomely for exclusivity, they are going to let readers read my works for free, and they do all the accounting?
Absolutely.
If I signed with Random House, they would have exclusive rights to my work. They would be the only people who could sell it. But worse: They would get to set the price, keep a higher percentage of the profits, and own my hard work until it, if ever, reverted back to me.
If you view Amazon as your publisher, everything they do is ten times better than any of the big six. Just the fact that I get paid monthly rather than once or twice a year is a huge deal. And I can leave at any time. It's amazing.