Right now you should be good to go to start using WASIX.
If you want to compile threaded code, things should already work (without waiting for any proposal in the Wasm space).
If you want to run it, there are few options: use wasmer-js for the browser (Wasmer using the Browser Wasm engine + WASIX) or using normal Wasmer to run it server-side.
No need to wait for the Wasm "proper" implementation. Things should already be runnable with no major issues.
is this something that is expected to "one day" be part of WASM proper in some form?