[on_and_off]

Kotlin also looks like the most serious contender to me. Sure, something like Rust might be more interesting for various reasons, but the engineering effort needed to port the Android framework to another language would be huge (and the official word from the Android framework team is that it is not worth the effort). Not to mention that third party developers would have to relearn the framework from scratch and that we either have a windows mobile 6 / WP7 rift or the framework team has another nightmarish problem to solve. Kotlin looks like it could both guarantee retro-compatibility with Dalvik and brings a better language to the platform.