Or maybe one of them kiwi deer hunters with a net gun in the backseat at all times.
Seriously: I do agree the drones should carry a transponder whenever flown out of the operators sight so they at least show up on the controllers screen, on TCAS, on PowerFlarm and whatever else is there in that department.
I predict that no drastic measures will be taken until an airliner is brought down by a drone followed by a public outcry. Apparently the incident in Warsaw with the Lufthansa Embraer was not enough for international consequences.