I have not yet read the linked paper, but honestly speaking it is not just IPC and async I/O where people don't use POSIX. For example many languages have their own non POSIX interface for managing threads and processes and I don't know anyone who likes directly using POSIX threads instead of some library abstracting over them.
If anyone wants to look into async IO here are some sources:
other techniques to look into, both for the good and bad parts (to prevent doing the same mistakes again) should contain: AIO (linux), IOCP (Windows), Singals, /dev/poll (solaris).
I personally would prefer a kqueue like API but it might be quite a big think to implement and I don't have much experience with system level async I/O. Also it has to be made with the Redox design principles in mind.