I think it shouldn't be impossible to establish a protocol for drones nearing each other to avoid collision and restricted zones. Of course, they'll all need to be equipped with a parachute and probably other forms of emergency damage control as well.
EDIT: the important damage to control would be that of citizens on the ground. I'm not suggesting drones should prioritize their own safety.
"Sense and avoid" is the current holy grail of UAV research.
Restricted zones have some interesting effects. DJI, a Chinese multirotor manufacturer, recently introduced 'no-fly zones' around airports for their ultra-consumer-level uav, the phantom 2. An unfortunate side effect, in the UK at least, is you are now unable to fly your phantom 2 in areas where it is perfectly legal to do so. I believe this limitation also effects where you can place waypoints on their more advanced autopilots.
They also prevent you flying over or near Tienanmen square...
EDIT: the important damage to control would be that of citizens on the ground. I'm not suggesting drones should prioritize their own safety.