You know what would get me away from Amazon for book buying? Lazy me? The kind of curated SF/F bookstore that he's talking about, the kind that used to exist in my city but closed ages ago, now in a digital version that's as easy as Amazon to use.
Yes, they probably couldn't offer Amazon's free shipping or bulk discounted prices, but I would pay a few dollars more if I had a default place to go when the book-buying itch hit me where I could RELIABLY and QUICKLY find fabulous recommendations of new genre fiction.
Features that would help -- books that have won major genre awards highlighted. Books listed by review site -- so that I could click on, say, Strange Horizons reviews, get the top-reader-starred recommendations at the top, and read through the reviews. Books recommended based on what I've loved in the past, of course. Books that everyone's talking about would be a great feature, since it's nice to be able to take part in the conversation at cons and such, although I have no idea how to implement that. And so on.
Frankly, I think that would be SO good for the field that I think it would be worth SFWA's efforts to adopt a bookstore and unleash a legion of volunteer geeks on upgrading its digital presence to make that happen. A typical bookstore owner probably has neither the time nor the expertise to make that happen. But this is SF, people. Surely we have some bored computer geeks who would kill for a great online SF bookstore?