I can report with unhappy certainty that at least the MD500D (I used to fly), but very probably all other helicopters, have a very short flying life left when any part of the rotating flight control system is no longer connected. This happened to the aforemetioned MD500D, due to a jammed and sheared swashplate, and the flight lasted only seconds more. There are just too many forces at work for aerodynamic trailing of the blade itself to keep it doing anything useful. There is certainly no "back up system" to assure this....
Pilot DAR