> My guess would be the kernel and/or JVM are on the next step list
I wouldn't bother integrating Rust into the JVM because there's limited security value. There may be ergonomic advantages in terms of project management but my hunch is that those are limited for something mature like Dalvik. If they rewrote it to use Futamura projections like Truffle, then Rust would be much more interesting as it would reduce the possibility of JIT bugs AND basically make it impossible to do a sandbox escape (most sandbox escapes target the JIT and thus other memory safety issues are rare & unlikely). Finally Dalvik security is unlikely to matter all that much because they rely on process isolation as the security model (Chrome does too but sometimes it loads multiple V8 isolates in a single process so V8 escapes are more valuable).
> My guess would be the kernel
There's already a Rust in Linux project & if you missed the news there's a lot of political in-fighting on the LKML. It's unlikely that Google has much sway here because even though they employ maintainers like Ted Tso, I suspect their influence on this matter is limited given how staunchly opposed he is & I doubt they'd be firing engineers like Ted over this. The Android team is going to have limited additional influence beyond what's already going on, but the Linux kernel itself is under no threat of being rewritten in Rust any time soon & Android isn't migrating to another kernel any time soon.