Thing is though, that there are better ways to communicate locally: AF_VSOCK is an alternative to AF_INET/AF_INET6 for local communication between VMs and hosts. In many ways it behaves very similar to TCP. It is similar enough so that you can just do ssh-via-AF_VSOCK. As opposed to AF_INET/AF_INEt6 it requires next to no configuration, your really just have to enable the knob in your VMM, and have a somewhat non-ancient Linux distribution as guest.
And ssh-via-AF_VSOCK is precisely what we are doing in systemd v256: a small new unit generator (i.e. a plugin that extends systemd's unit tree dynamically) detects if AF_VSOCK is available and sshd is installed, and if so binds AF_VSOCK/port 22 to sshd, via socket activation. Or in other words: in environments where AF_VSOCK is a thing, sshd will now *just* work, without any extra configuration and at minimal cost of resources (because lazy socket activation rocks).