Very good questions! I still need to flesh out the patterns. While streams of streams are common in functional programming environments, I simply haven't seen them in class based streaming patterns anywhere so they're things to figure out.
Of course, more streams means more resource utilization, there's not getting around that, but that's the cost of parallelism. The use of `yield*` should keep the overhead to a bare minimum. Since the streams are being left alone and aren't consumed until needed, that should preserve some of the back-pressure behavior, although I do need to look into that more deeply.
How the system handles errors probably doesn't have a single solution that works for all frameworks, so I think it should be up to the specific requirements of each use case, but there's also definitely more work to do to explore the options and the patterns.
These are all things I definitely want to hear ideas for as well!
The next thing I'm exploring is applying these patterns to web rendering which will be a real stress test for how they can be used.
