I has been served for several decades, however since the late-90's many decided reducing to only C and C++ was the way going forward, now the world is rediscovering it doesn't have to be like that.

They're are certainly going to be lots of languages because now with LLMs it's easier (trivial?) to make one + library (case in point: just within last month there're have been posted here ~20 new langs with codebases 20k~100k LOC) but don't really see them competing. Rust and Zig brought actual improvements and are basically replacing usecases that C++/C had limiting the space available to others.

Uhm, no? There is barely enough space for Rust, which happens to have a unique feature/value proposition that raises it above the vast majority of its competitors. If you're fine with UB or memory unsafe code, then you go with C simply because its deeply entrenched.

In that sense Zen-C changed too many things at once for no good reason. If it was just C with defer, there would have been an opportunity to include defer in the next release of the C standard.