As some respectable C developer I know says: the issue with the C "killers" is that the people that already know C, have years, decades and experiences they are unwilling to let go. They can jump across any major systems programming project out there and feel at home.

So to win these people you need to have a killer feature that can win them, Rust offers it. The Jai, C3, Zig, etc, do not.

Sure, they are better Cs, but that's not enough to switch.

So eventually, all those C killers will keep growing, among newer system programmers, but not much among seasoned C devs.