Good news! WebAssembly has community group projects setup for both multithreading [0] and multi-memories [1] which would allow a module to both define a memory space and also import a shared one.
There are so many parties interested in wasm, there are a ton of inflight proposals and extensions to get it beyond the mvp stage.
There are so many parties interested in wasm, there are a ton of inflight proposals and extensions to get it beyond the mvp stage.
[0]: https://github.com/WebAssembly/threads [1]: https://github.com/WebAssembly/multi-memory