Mainly, there’s a good chance Jacob will have progressed the x86_64 backend far enough that we can enable it by default for Debug mode on ELF targets.

That sounds a lot like self-hosted code generation. I wonder if this is a significant step toward bringing async back to Zig.

For the relevance, see the FAQ:

https://github.com/ziglang/zig/wiki/FAQ#what-is-the-status-of-async-in-zig

Note especially the last three bullet points.