If there's one truth I've learned in my decades of dealing with computers, it's that you can't beat C at being C.
Before now, I'd never heard of Zig in particular, but I can think of several other languages that have tried or are currently trying. A lot of people seem to think they can make something a little better than C, in some ways, and that will be enough. I doubt that even C18 itself, if it were invented from scratch today, would be able to unseat another systems programming language.
Everybody forgot about Worse-is-Better: "Unix and C are the ultimate computer viruses". Any language which isn't more 'viral' than C (in terms of being ported, and attracting users) has no chance. You're starting tiny, and growing less quickly.