Nothing is guaranteed. But just because a remotely operated vehicle is out of physical sight doesn't mean it is out of control. First off they shouldn't be operating anywhere near aircraft, drone flight should be restricted below 500' (planes, jets and helicopters are supposed to remain above this altitude), above 300' unless they have the permission of the land owner to fly lower and nowhere near airports. And no one in their right mind is saying that these things should be allowed to fly about unmonitored. But if you have someone monitoring the video and/or telemetry from each drone it should be as good as line of sight and shouldn't overly effect their usefulness. If the drone up/down link fails the drone should either return to base or immediately and land. Requiring line of sight makes them virtually useless, I saw a University presentation on their working with the FAA's program (about a year ago) beyond the obscene paperwork requirements to do a survey of a relatively small 10 acre field required a half dozen people. Imagine two scenarios both surveying the same 50 acres of woods. In scenario one we have the line of sight requirements, they either have to post people with some form of control of the craft every few hundred feet, requiring dozens of people thereby putting many more people under its flight area. Or move a few hundred feet at a time with one or two people, either way it would either take a full day or even days. Scenario two, a single van with a single person pulls up next the woods, they set the drone outside and press a button in the van, the drone goes about its work with the person monitoring it from inside the van. Even if the drone had to come back for battery swaps it would probably take a few hours and the one person that is in the operations area is safely in a van where they cannot be struck even if control is lost.