The main promise of Centennial apps is that they are the same apps which developers are already distributing via their websites, meaning developers do not have to do anything special to keep them up to date beyond what they are already doing for their non-store apps.
It seems that promise is becoming a reality, with both the Amazon Music and Spotify Music apps receiving updates this weekend.
The Amazon Music app has of course just been released, and the new update appears to have the same version number (126.96.36.199) as the release version, so presumably only addresses minor bugs. Unfortunately, both updates are without a changelog, which is somewhat traditional for Spotify, which is now version 1.74.380.
With the promise of iTunes eventually coming to the Microsoft Store, it seems, at least when it comes media players, Microsoft’s current strategy has finally achieved some traction.
The apps can be found in the Store here.