I'll second this: when I buy a book, I want to own it. DRM means I'm constantly at risk of my "ownership" being revoked. So I always try to buy the non-DRM version.
In recent years, I've found that Amazon's Kindle store has become less good. Their recommendations are much worse than they used to be, their handling of book series is bad (if a book is in a series, show me them all, in order, and identify those I already own), the pages are just awfully messy and cluttered, they push Prime in my face all the time, etc, etc.
I'll love a great, curated online book store. Much like a real bookstore, have things organized well, have staff recommendations (not random bot-boosted rubbish); focus on authors with interviews, and AMAs, and so on; and make it a nice place to browse (and buy).
If you make the commercial deal for authors/publishers decent, I suspect you would be able to build a decent list of suppliers. And if you focus on the "good bookstore" feel, I think you've got a good chance at some success.
