Various OpenBSD devs have had mixed (at best) feelings about Rust, recognizing it as a language that is by no means a silver bullet for safe code. Part of this was/is also flavored by the fact that LLVM (and therefore Rust) supports only a subset of the hardware platforms supported by OpenBSD.

However, now that OpenBSD is continuing to switch from GCC to LLVM/clang as the default C compiler for an increasing number of targets and as an increasing number of non-LLVM-supported targets are discontinued, I reckon the idea of some or all of OpenBSD being incrementally reimplemented in Rust is - bit by bit - becoming a little less far-fetched. It also helps that Rust is liberally-licensed.

That all said, I'm not really holding my breath for that happening anytime soon. Until then, Redox continues to look interesting.