I've submitted a request to have you banned. Look at your history. You contribute nothing and just spew annoying nonsense. Adios.
Sure it can. Why couldn't it? At worse, you could write a multi-threaded C library and have emacs/emacsclient call into it.
That's why I said that model needs to be extended. There's no reason emacs server couldn't send stuff over a TCPsocket to emacs client. Emacsclient and emacs server are separate OS processes, so they already communicate via external mechanisms.
I almost exclusively use emacs --daemon and then emacsclient to connect to it.
In my opinion, this model needs to be extended so that emacs daemons can't accept connections over a network. Maybe piggybacking SSH, or some other socket protocol. Of course, never could administrators would have to enable that port, so there are complications in professional environments.