If this becomes a big enough problem, we might be able to build a work-around into the Cloudflare Workers Runtime itself so that it can support synchronous waits. It'll take some hacks but I think it's doable, without actually supporting threads.
I'd probably use fibers, like node-fibers used to do. The problem is V8 stopped supporting fibers a few versions ago. We'd have to hack support back in. That's something we probably could get done but I'm not exactly excited about it. :)
