As one of the new breed of 'drone' operators, I have a vested interest in this thread. I would like to deal with some of the issues raised and respond with opinions based on operating in the UK.
Conflict with any other air user and especially commercial aircraft should never happen. Of course it does, and as sub 7kg drones are currently permitted to operate in controlled airspace without clearance, will continue to happen. Recent CAA rules, now allow sub 3.5 kg drones to operate at up to 1000 ft AGL flying FPV. In other words, the pilot is sitting on the ground with goggles on, flying with just the view ahead.
The threat then, is from untrained leisure flyers with little knowledge of the hazards and rules. Recent CAA action has been to ask anyone reporting an airprox to notify Police asap. Prosecutions are taking place and awareness of 'rogue' operators to the possibility of prosecution is growing.
Commercial operators such as ourselves must undergo training and flight assessment which whilst not as rigorous as a PPL, is similar in content. We must also produce an Operations Manual, which of course must be adhered to at all times.
We do operate occasionally in controlled airspace, but always with permission and contact with the relevant ATC. In any case, we are normally restricted to below 400ft AGL. Should any of the control systems fail, the drone must have a return to home capability. If the worse should happen, a fly away, we always have the contact details of the appropriate ATC.
Most of the work we carry out could not be undertaken by full sized aircraft. Some of it could, but a drone is often safer in these circumstances.
A previous post alluded to the fact that most injuries and fatalities associated with model flying are suffered by the participants. This is true though there has been at least one fatality to a third party. Traditionally, model flying has taken place at club sites. This has kept the public and other air users safe from the activity. There is a growing trend of 'park flyers', who are generally free of rules, instruction and insurance. This cannot be a good thing for anyone.
The future of drones depends on the development of a creditable sense and avoid system. This is not far away. Then it really will be a fight for space!