I don't think Andrew believes Zig is going kill C or C++, he probably has hope but I think he is aware of the reality. He found a way to make a living on something he was passionate about.

Use-after-free is a fact of life until something kills C, but the realities of language adoption are against that. Zig seems interesting and worthwhile in offering a different perspective on the problem and does it in a way more agreeable than Rust or the like for all those who love C and are adverse to large complex languages. The realities of language adoption are as much for as against Zig, large numbers of people are still getting drawn to C and Zig seems to do a better job addressing why so many are drawn to it than the alternatives.