reg. Aerial delivery via drones..
first, payload needs to be increased first for deliveries to become truly useful (in a survey conducted just few months ago people were asked what they would prefer to have delivered via drones -> it was small gifts and emergency medicine which are still light enough)
second, aerial delivery via drones opens another potential legal minefield (nevertheless of autonomous systems for the drones themselves) in terms of responsibility should the goods be dropped by accident/failure..
nevertheless DHL, UPS, DHS, Amazon, Alibaba and Google are already experimenting on aerial delivery systems.. most promising system here is a quadcopter thanks to hovering abilities, but also other systems are being explored with.. stay tuned, aerial delivery may become a reality (at least in europe and asia thanks to absence of FAA) sooner than most here expect..
still, there will be many other aerial applications being commercially available (inspections, investigations, monitoring, conservation, broadcasting etc..) before aerial delivery becomes a norm..