You still have the issue of not having an implementation of an Ethernet or network virtualisation features like Crossbow/VImage. Even if you were to solve that

You still have the issue of not having an implementation of an Ethernet or network virtualisation features like Crossbow/VImage. Even if you were to solve that you would be stuck with the VFS graph driver unless you could get a CoW filesystem up and running on OSX (maybe revamp the old ZFS port?). Docker is much more than just jailing is basically the problem.