I think Linux is going in the direction of "everything is a dbus API" instead. Linux needs it's own "9P," or equivalently practical, if it wants to reverse this trend. DBus, while perhaps not the best IPC mechanism, currently fills the gap. Several of the systemd binaries are there purely to shift from reading and writing files to pushing updates over dbus. See for example systemd-hostnamed.
Isn't linux advancing in similar direction, except that everything is a file descriptor (even processes are now!) instead of a file bound to the directory tree? And technically, everything that is a file descriptor is also a file, thanks to procfs.