Without a GC WASM is very hard to use for regular web development tasks. When GC infrastructure lands lots of mind-blowing stuff will happen. Things like JVM and .NET running in WASM.
A lot of web people don't realize magnitude of impact WASM will have on the web.
To get good performance on running JVM or .NET WASM will probably need more than just GC support. JVM/.NET JITs rely on inline-caches that aren't currently expressible in WASM. There are ideas about ways to make this work, but it will be a while.
The other thing preventing the use of JVM or .NET is that porting the runtimes over isn't easy. i.e. You can already run this bytecode in a browser but it isn't widely used. (http://jsil.org/, https://github.com/decatur/j2js-compiler, https://github.com/plasma-umass/doppio, https://github.com/mozilla/pluotsorbet etc)