I just know one thing: the moment Kindle is removed from the app store, I'm selling my iPad.
I'd love for Amazon to remove the DRM from their books, and just sell books in epub format which can be read on any device without a Kindle app. That would solve Amazon's problem with iOS/Apple, and also be an ideal solution for end users. EDIT: what I mean is, music is now sold without DRM. Why do we still need DRM for ebooks? I'd love to be able to just put all my ebooks in a Dropbox folder, and not depend on Amazo…
Both companies sell IP - and both rely on a various forms of DRM to enforce scarcity. I think selling IP will eventually be seen as a fruitless (and unsustainable) pursuit - but for the time being this is a way both these companies are making a profit selling digital goods.