Most interesting thing about this is the use of Amazon Appstore. It's like Microsoft is acquiescing by not trying to build yet another app store (even an Android store) and lure developers and support costs along the way.
MS is probably aware that Amazon could see this as a backdoor into Windows software licensing too.
I think that it has more do with Microsoft not wanting to build their own replacement for "Google Play Services" just yet. Amazon has a decade or so investment in their alternative to "Google Play Services".
