First and foremost Chrome has to get onboard. Hardly anyone cares if Mozilla implements anything.
A few people will care if Safari does.
Edge is out if the picture and is being replaced by Chromium (aka Chrome).
On WebAssembly specifically. Here’s WebAssembly working group: https://www.w3.org/2000/09/dbwg/details?group=101196&order=o...
I count 18 people from Google, and only one from Mozilla. The second largest representation is from Microsoft (8 people), but their input is now Chrome/Chromium input.