I think integrating UAVS into the existing flow of air traffic is a big challenge. Air traffic control can be the mechanism, I suppose. It tends to require radio responses that a UAV can probably acquire.
Reserved airspace is the way it's handled now, but I don't think that's the solution forever. They're in small numbers and so it can be done that way. The Federal Aviation Administration in the U.S. has been given a target date of next year to come up with the procedures and process in order to integrate UAVs into regular general aviation.
I'm not given any reassurances that's really going to come to pass.