Interesting! I'd certainly say that's worth something. Definitely didn't expect it though given how poorly some people have reacted to Rust being introduced as an optional part of the Linux kernel.
rustc_codegen_gcc is close to becoming stable, and conversely the Linux kernel is dropping more esoteric architectures. Once the supported sets of architectures fully overlap, and once the Linux kernel no longer needs unstable (nightly-only) Rust features, it'd be more reasonable for Linux to depend on Rust for more than just optional drivers.
However, adapting the conventions and mechanisms of a large complex C system like the Linux kernel to Rust is taking time.