Programming languages never die, so I don't have a personal opinion on this point, exactly. For me, I would only write C code if I was working on a C project, or if I couldn't get a Rust compiler for the target platform. My starting point would be Rust, it would have to be disqualified for me to use C. Then again, I am the most biased person possible... (and also prefer C to C++) But regardless, C will never, ever die, so talk of Rust 'killing' or 'replacing' C is misguided, in my opinion.