I don't think a server-side sandbox makes sense for anything that is JIT-based (or even binary translation). We already have KVM which is actual native performance, and it can run anything you would ever want, and then some. WASM is bytecode working on a 2GB linear arena, and it fits OK in a browser.
I don't think that's really the use case I'm describing. Maybe I'm doing a bad job, I dunno.
The use case is essentially user logic for event stream processing, where the events are things like "received an email" or "clicked a link" or "3 days have passed". You're not going to spin up a KVM for every contact on a 2 million member email list even if you're using Firecracker, but executing a WASM blob for every event might be feasible.
The 2GB limit was a temporary browser limitation. Modern browers mostly support 4GB now. And wasm64 is testable today, which supports 64-bit pointers and more than 4GB.
