Meeting real-time guarantees pretty well isn't good enough for a DAW. Not without a lot of buffering (and therefore latency), anyway.

The WebWorker proposal is interesting. If the worker has its own heap and realtime scheduling with a correctly configured GC, it would be a big improvement.

Getting the different implementations to work consistently enough will be challenging, though. Meeting realtime deadlines is difficult enough when working in C with a known OS and audio stack.