Quite simply there haven't been any candidates so far which both got the "essence" of C and had the momentum to actually replace C. Zig looks like the most promising so far, if they don't fuck up on their way to 1.0
(disclaimer: I switched back from C++ to C as my language of choice for writing libraries ca 2017, but also continue to write C++ (if necessary to talk to C++ libs) and a lot of Python and Typescript for simple cmdline tools and web stuff, also ObjC on Mac of course for talking to system frameworks, in recent years dabbled with Rust, Odin and Nim, in the long distant past also with C#, Java, Lisp and some Forth, and eventually hope to transition over to Zig for the stuff I currently use C for (maybe in 3..5 years?)
TL;DR: use the language that suits a problem best, and C is a very good tool to have in any language toolbox, because it can usually provide a solution where other languages have to give up or just become to much of a hassle (for various reasons)
(disclaimer: I switched back from C++ to C as my language of choice for writing libraries ca 2017, but also continue to write C++ (if necessary to talk to C++ libs) and a lot of Python and Typescript for simple cmdline tools and web stuff, also ObjC on Mac of course for talking to system frameworks, in recent years dabbled with Rust, Odin and Nim, in the long distant past also with C#, Java, Lisp and some Forth, and eventually hope to transition over to Zig for the stuff I currently use C for (maybe in 3..5 years?)
TL;DR: use the language that suits a problem best, and C is a very good tool to have in any language toolbox, because it can usually provide a solution where other languages have to give up or just become to much of a hassle (for various reasons)