I hope that someone in the 40 comments i don't have time to read right now has pointed out that the premise of OP is flawed for the simple reason that Rust hit v1.0 in 2015, while Zig is still nowhere near that milestone in 2024.
So we are not even talking about the same "future" period from the start.
So, no need to get to the second false premise in OP, which is limiting a "future" period to one successful dominating language only. Nor is there a need to go beyond these premises and discuss actual language details/features.
I don't know, and I don't want to get personal. But that's usually a sign of someone who doesn't even code (at non-trivial levels at least)*, and thinks programming languages are like sport clubs, developers are like players contracted to play for one and only one club, and every person in the internet gantry need to, for some reason, pick one club (and one club only) to be a fanboy of. Some people even center their whole personality around such fanboyism, and maybe even venture into fanaticism.
So each X vs Y language discussion in the mind of such a person is a pre-game or a pre-season discussion, where the game or season is an imaginary competition such people fully concoct in their minds, a competition that X or Y will eventually and decidedly "win".
* Maybe that was an exaggeration on my part. Some junior developers probably fall into these traps too, although one might expect, or maybe hope, that their view wouldn't be that detached from reality.
I'm hoping to finally finish and send out a delayed new release for one of my older and mature CLI tools this weekend. It's written in C btw 😄