Abstract sockets have no permissions. Not having to deal with the filesystem at all is nice, but having absolutely no security model whatsoever also seems dangerous.
You have the ugly issue of having to deal with handling zeroes in your name, as noted in the article. This can and will break something, somewhere on the first attempt of writing it.
When you want microkernel IPC, you usually tend to want a message-oriented reply-and-receive primitive to main loop around them. Emulating this with sockets is error-prone since send(2) and recv(2) make extremely weak promises about their behavior on error. sendmsg(2) and recvmsg(2), which are necessary to pass kernel objects around (i.e. file descriptors), are very difficult to use.
Sockets are nice because you can select(2) etc. on them, however. I'd expect a replacement would interoperate smoothly with at least those system calls.