Everything you've outlined are concerns for developers, not for Google or Amazon. And as painful as it may be for small, independent developers...we're not what really matters in these ecosystems. Regardless of who owns the app store, we're going to stay irrelevant.
The real dollars are in commerce, search, and the gateway to these is going to be mobile. That's the real implication -- not a few hundred thousand developers getting yanked around and having to go through 4 app store approvals processes instead of 2.