Actually it was installed in the simulator so Delta could train their pilots there as they had the HUD installed on their classic fleet. And the classic can do normal dual autopilot autolands for cat 3 anyway.
And it is installed on the BBJ as standard, that one has fail operational autopilots with auto-rollout as well, of course that is not used in airlines but is certified to the same standards.
The 787 will come with dual HUGS as standard, although the autopilot system most certainly will be able to provide CAT III capability without it, will be interesting though if you can do manual CAT III landings with the HUGS alone or if it is just there to provide head up flying in all types of approaches will be interesting.