For my use case of building Filestash, WASM is a game changer in those 2 areas:

1. use libraries from ecosystem outside JS. In the past few months, I've added support for file types like psd, dbf, arrow, parquet and about 50 more. To give a concrete example: https://www.filestash.app/tools/parquet-viewer.html WASM open up a very exciting door. In the same idea, I stumbled upon a couple JAVA only libraries which I would love to ship on a browser and not have to create web service to interact with those.

2. enable third party to make plugin that can run in my app in a safe way. In my case, plugins are zip files containing a bunch of assets and the WIP piece is to be able to put wasm in there that will run server side without giving those plugins a blank check for acting crazy.