Nice.
Now please make C# a first-class citizen in Android and start to migrate from Java to C#.
Google have not made their own languages Dart/Go official to Android. Why would they make languages other than Java a priority now?
Dart doesn't have the adoption yet and has a different plan when it comes to mobile ( https://github.com/flutter/flutter ).
I love Go, but it's not really a suitable language to do UI, or anything that deals with data models.
C#, however, is a perfect replacement for Java, most of the times. I would say "it's simply superior in every imaginable metric other than cross-platform implementations of the compiler/VM" but that's just my opinion.