[Zigurd]

Android is deeply dependent on a runtime with Java semantics. The only realistic hope for an implementation language other than Java would be a VM language like Scala or Kotlin. Kotlin is a semi-official alternative, since it is supported by the IDE technology provider.

C# is close enough that ART could likely be extended to encompass it. But it would be somewhat more work than supporting an actual JVM language.

BUT the real question is, with modern IDEs, does it matter? How much do you need a prettier and/or more concise language? And if you do, why not Kotlin?