This discussion is pretty interesting to try to list when each architecture is the most efficient, based on the need.
However, just a small precision: multiprocess/multiworker isn't antinomic with AsyncIO: You can have an event loop in each process to try to combine the "best" of two "worlds".
As usual in IT, it isn't a silver bullet that will care the cancer, however, at least to my understanding, it should be useful for some business needs like server daemons.
If you want to use any AsyncIO server protocol (aiohttp.web, panoramisk, asyncssh, irc3d), you can use API-Hour: http://www.api-hour.io
And if you want to implement by yourself this design pattern, be my guest, if a Python peon like me has implemented API-Hour, everybody on this mailing-list can do that.
For communication between workers, I use Redis, however, you have plenty of solutions to do that.
As usual, before to select a communication mechanism you should benchmark based on your use cases: some results should surprise you.
Have a nice week.
PS: Thank you everybody for EuroPython, it was amazing ;-)