Good point! Regarding C being the language of choice for mission-critical systems, probably you want to avoid memory bugs that might result ruining the mission. I understand many projects have large C codebases or interact with other projects in C, but migrating to Rust when possible (like replacing lead pipes as you find them for plastic pipes) sounds like a smart choice to build mission-critical low level systems.
If with "production software" you mean large pieces of software I'd generally agree.
I personally like Zig but I'd never write a huge 200k loc project with it, I see it more fit for low level stuff like small embedded devices where you must interface with C code.
eventually, they fell back to rust.
there's a lesson here: subset languages are fine for experiments and small projects, but they're rarely the right choice for production software.
...and C still can't be replaced. it's still the language of choice for mission-critical systems and low-level problem solving.