> I don't see how the two languages might coexist peacefully without rust toolchain being necessary for building any kernel useful in practice and anyone seriously involved in kernel development having to be proficient in both languages.

I can empathise with that. Just last week I butted head with an issue in a python package that requires Rust internally. The lib compiles fine on its own, but something gets screwed when running in a virtualenv. Opened a bug in github, and nobody has any idea about how to get even a detailed log out of the rust toolchain.

I'm sympathetic about Rust, I really am. But sprinkling it mindlessly everywhere is a big risk.