I wonder if it would make sense to rewrite some native components of Android in Java now. Presumably, whole-program optimization means that the ART compiler is more effective if more of the code is in Java (or technically, Dex bytecode) rather than having opaque native parts with JNI overhead.
A lot of Android is written in Java already. What would be interesting, however, is Android transitioning to a message passing micro-kernel (instead of Linux) and writing as much as possible of the rest of the kernel in Java.
That is already the case. When you look at the NDK, you can only have access to game related API (audio, graphics and sensors) almost everything else involves JNI.
