SharedArrayBuffer is a nice primitive that allows multiple Threads (or WebWorkers) to work on data in parallel. The additional primitives they're proposing offer quite a bit of flexibility. For one, I would really like an easy `new Thread(fn).asyncJoin()` to create a Promise to do expensive CPU-bound work. There are a few npm modules that do some version of this but it can be slow.
As for the concurrency model, it should be possible to delegate tasks to a pool in this one. Map an array of input data and functions to an array of promises, then Promise.all() or Promise.race() on them.