No. It requires bundling some code in apps and back-patching older Swift runtimes to cope with the new model.
Back-porting requires work deep in the runtime and compiler. Much of that work is understood. I don’t think this discussion will produce new insight into that work; the insight will come from doing it.
The best thing the Swift community can do for the concurrency effort is to try out the features on their own code. Even if you can’t ship it. Find the rough spots so we can smooth over them. Find the latent bugs, the design oversights, the ideas that are hard to communicate. Write the tutorials that make all of this more accessible to more people. We have time to make the model even better.
Concurrency is already supported on these platforms as part of 5.5. They don’t benefit from OS integration, so their performance characteristics aren’t as well understood.
Not really. The tricky part of back-porting is the back-patching. It’s a different set of concerns than bringing up an implementation on a new platform.
Doug