Yeah, my interest in this is for server-side purposes. I can imagine wanting to build a feature that allows users of my web application to write and execute their own custom code - think triggers and hooks for custom logic.

If they're creating code that will run on my servers I need to have an EXTREMELY reliable sandbox around it - I see WebAssembly as providing the best possible option for that these days.

Letting them write their customizations in JavaScript which I then execute in a JavaScript interpereter inside a WebAssembly container sounds like a pretty good option.