No real world experience, however we tested that in the simulator when we received our recurrent CAT IIIb training on the 737. With the loss of the ILS signal below 200ft the autoflight system remains in LAND3 status and will continue the landing, do the flare and touch down in the touch down zone. However if the wind changes during that time there will be absolutely no drift correction and the aircraft will drift accordingly. Which could lead to a very nasty experience. Both the G/S and the LOC FMA will turn amber, and for us it is a mandatory go-around because of the safety issue with the drift.