CAT IIIB CATIIIC relies only on instruments (meaning Guidance),
Yes in reference to the ILS but I have never known any operator to certify an aircraft cat IIIb w/o a minimum of 2 autopilots, sure the flight director will continue with rollout but what is the point if you have been met RVR minimums at 200-300 feet.
I have not heard of FLIR shutting down at 100 ft agl, I suppose it may be specific to the aircraft you are operating. I work with single EFVS systems, great to get you off the ground in foggy weather and enhance safety in the muck.
There is talk about CAT IIIC certification for the aircraft as our flir computer has a second output if we continue with the instalation in the F/O's position as well. To correct myself it would bring RVR down to 0.
Commercially it is still a system that is under continuous development and federal approval.