Maybe I'm a bit of a rust fanboy and a bit of a skeptic but
Zig and Jai aren't going anywhere. Zig appears to be a largely single contibutor (https://github.com/ziglang/zig/graphs/contributors the creator has < 2/3 of commits).
Jai does not have a public compiler and is not likely to get a public release anytime soon.
As for rust we don't know yet how big of a chunk of marketshare it will take from new c and c++ code.
Not many people still use c code for "everything", most have already switched.
What is the actual argument that you support with pointing out that Zig is "largely single contributor"? Linux was largely a single contributor up to a point.
There is nothing wrong with single contributor languages. But for every C there are thousands of flatlined github repositories of single contributor languages. Building a language is a marathon, not a sprint. It takes years and years to grow something worthwhile, and this requires a lot of persistence. In the meantime, technical challenges, finances, family, and even busses get in the way of languages being fully realized. Having a team rather than a BDFL increase the chances of a language flourishing and persisting.
Aside from starting Zig as his personal project, Zig is also Andrew's job now. As far as I'm aware that is not true of any other contributor, so it makes sense he'd have the lion's share of contributions.
Zig and Jai aren't going anywhere. Zig appears to be a largely single contibutor (https://github.com/ziglang/zig/graphs/contributors the creator has < 2/3 of commits). Jai does not have a public compiler and is not likely to get a public release anytime soon.
As for rust we don't know yet how big of a chunk of marketshare it will take from new c and c++ code.
Not many people still use c code for "everything", most have already switched.