Mobile apps and services. Or an OS. Essentially, Amazon throwing in the towel on pushing their own Appstore indicates confirmation that, in fact, nobody can compete with the Play Store. And since the Play Store is illegally tied to a couple dozens apps as part of Google's Mobile Applications Distribution Agreement, it's a monopoly that extends far beyond just an app store.

Actually, that bears an interesting question: If Amazon actually were to release such a phone, unless Google makes them a special exception in the standard MADA, Amazon would have to agree to either switch Kindle Fires away from Android or start putting Google Play (including very direct competitor apps like Google Play Books) on Kindle.

Google forbids any developer who has access to the Play Store from selling any so-called "incompatible forks" of Android.