IMO Zig is the best C replacement (maybe after a few more years of development), but I still think Rust is the best C++ replacement. Personally, Rust is my most productive language, even more than Python/Scala/TypeScript etc but I don't think it fills the same spot as C for when you really need completely manual inherently unsafe and tricky memory management.

I won't tell you to become a hairdresser, but I don't see why having a steep learning curve is necessarily a bad thing for a programming language. Even if Rust is complicated to learn, it's nowhere near as hard to understand as the problems it's meant to solve, so engineers can still be expected to learn it.