For my work code, it all comes down to SDKs and stuff. For example I'm going to write firmware for Nordic ARM chip. Nordic SDK uses C, so I'm not going to jump through infinite number of hoops and incomplete rust ports, I'll just use official SDK and C. If it would be the opposite, I would be using Rust, but I don't think that would happen in the next 10 years.
Just like C++ never killed C, despite being perfect replacement for it, I don't believe that Rust would kill C, or C++, because it's even less convenient replacement. It'll dilute the market, for sure.