Yes it's been in phase 3 for what like 2-3 years at this point (judging by when it landed in browsers)? No eta and no next steps. The tp says they are waiting until "it's stable" so I'm assuming phase 4. It qualifies browser support and "at least one toolchain" criteria[0] (zig) and seems like all the other conditions too except maybe "CG consensus" whatever that means, so for all I know it could take anywhere between tomorrow and in a few years from now...
https://github.com/WebAssembly/proposals
You can also check out:
https://webassembly.org/roadmap/
And for Go, the proposal project on Github has many interesting conversations from the devs.
And as a reminder to anyone interested in using Go WASM, it’s experimental and does not come with the same compatibility promise as Go itself:
https://github.com/golang/go/wiki/WebAssembly