I ported C compilers (badly) and manage people who do it (well.) Today you port LLVM, either yourself or using a commercial LLVM backend generator. This makes Rust nearly as accessible as C (in that the platform vendor will bundle clang with some platform-specific extensions but not a Rust frontend with similar extensions. But the heavy lifting is the backend.)

This is not to say that Rust will spread like wildfire, just that porting C isn't easier.