The most interesting killer application for Zig is perhaps Ghostty and its library libghostty, which will probably be fairly easy to integrate with C apps since Zig is close enough to C.

There’s also Tigerbeetle, but unlike libghostty its use of Zig doesn’t have much chance of being viral.

I think libraries that can be used by many other languages is Zigs chance to wide adoption. And this ties nicely with Zigs fantastic build system, which may become increasingly popular for C based projects, especially where cross compilation is important.

Hardly something to make FAANGs adopt Zig, and make it unavoidable for everyone else.