Nothing can replace Java for android, unless it can also replace all the libraries current Android application is replying, which is the reason why I believe Google isn't going to switch off Java anytime soon.
I doubt it will be officially acknowledged by Google, but hey they never acknowledge third party good things, and the official Android developers docs still tech us to do networking with HttpUrlConnection and threading with asynctask, we moved on to okhttp and retrofit and rxjava anyway
There's no reason why it can't be reversed, with Xamarin (or something along these lines) becoming the new native high-level API, and Java being a compat layer on top of that.