What I like about rust is how I think it will go together really well with a language like idris. The idea is, whatever rust cannot guarantee an idris-to-rust transpiler can. People should have a much easier time making solid low-level code in the future.
Unfortunately safety is not the only concern. Idris' tooling is severely limited. There are very few executables written in Idris (and even fewer that aren't bit-rotted), the build tooling and package management are very simple, the runtime is heavily optimized, concurrent or parallel (like GHC's) and the single-threaded performance is far from Rust's.
I want to be clear that I'm not hating on Idris I love the goals of the project and am probably one of the few people outside the core contributors who has written a backend for the compiler, but you can't really compare a production quality compiler with a full time team of 10 or so to a research compiler worked on by researchers (who have different goals) and volunteers.
Edit: To clarify for this reason I could see why it would be cool to be able to write some critical code in Idris and extract to Rust where you could get performance and tooling for the rest of your application.
I can't really imagine rust being a better target than C-- or something at that point, as you've got an infallible machine managing your memory already. If you output code that is rejected by the rust lifetime checker, you've still got a problem.
