Actually it should be cheaper than the existing transponder so the small planes should have this. Yes we will need some controllers if only as policemen, but eventually every airliner and the more expensive small planes will have a screen that will show the traffic and include CAS which is much better than existing so the controller will be mostly assisting the smallest planes and acting as a traffic cop. It will greatly reduce the numbers, and eventually with improvements such as automatic violation recording, then their will be no need for controllers other than for ground control and emergencies. Oh and processing those automatic violations.