Comment by Mawr

Switching out the entire ecosystem, libraries, tooling; rewriting the entire codebase; learning the new language and its idioms; and then giving up the unknown benefits of the previous language that the new language lacks (for Go->Rust this could e.g. be compile times)—generally, trading known downsides of a language for unknown downsides of another—is a huge undertaking and therefore very unlikely to ever be worth the hassle.