If anything, Amazon knows this will really incentivize updating your Android app on the Amazon App Store, or bringing it there if you haven't. And that's good for us because, should the Amazon App Store become more viable for manufacturers, Google might find themselves increasingly losing control of Android, and increasingly forced to make the Play Store more competitive.
This is an absolute win-win for Microsoft and Amazon. Microsoft gets Android Apps, Amazon expands its app store and Google is shunted out of the Microsoft eco-system. I see this as an absolute brilliant thing to happen to the app ecosystem. I really hope innovation accelerates on the Amazon App store.
Seems like all the major OS are betting that mobile is going to be the focus of future native app development and don't want desktop users to miss out.