While i truly love Go as a language i think it might still not be mature enough to be used as a full fledged language for Android. The garbage collector is still not mature and could use some optimizations.

You also call Java a systems language. I'm not sure i agree in that view since you don't have direct access to the hardware it runs on. You're still running on JVM which does jit compilation of your code. Java is a high level language falling into the came category as the .NET languages and Python.

I would still very much see Go on android as a fully supported language. Go is beautiful.