The TC39 process: https://tc39.github.io/process-document/
In terms of chances of standardization, that's a step up from "Hey, I have a great idea", buy there are plenty of Stage 0 proposals that go nowhere because they lose steam.
I think the metric they look for is who is using the Babel plugin for it. If people are doing that, then they it has a better shot of progressing.
Stage 4 is the "this is getting standardized next time" stage
The closest thing I can think of is ES6 modules, because the module loader spec wasn't finished, but the syntax still lived on.
Now, stuff getting kicked down from Stage 3, that has happened.
Basically, it's just a proposition for the moment, there's no telling if that's gonna be in the language or not. It's only at stage 2 that it is likely that the feature will be added in the language.