Go on Android would be great, but Google used Java in the first place so that they could leverage all the Java devs in the world to build Android apps.
Go might be a much better choice from a pure dev standpoint, but from a getting everyone to build apps standpoint, it's a fail in the short/middle term.
I didn't say get everyone to build apps. It would simply be another option. App development is getting more competitive, of course, so people that want to stand out might need to move to Go to gain an edge. Plus, I image that a Go environment might provide a better interactive development cycle.
Go might be a much better choice from a pure dev standpoint, but from a getting everyone to build apps standpoint, it's a fail in the short/middle term.