For a while I have thought that a cool way of doing this would be if the drones could fly close to high voltage power lines and use induction to power it and charge the battery. Then when it gets close to the destination it could peel away from the high tension lines and use battery for to cover the last mile. That way you could have the warehouse in some industrial area or whatever. They could make a deal with the power companies and those lines could be like the arterial lines for the drones. I have Googled around and this is not a new idea but I have not seen anyone try it or test it, at least not from the searches I have done. I believe it is feasible as those lines are 500KV and as a drone moves past it, there is a significant EM field around it and an inductor lowered down 20 feet or so from the drone could pick up enough power while maintaining a safe distance. Has anyone else heard of such a thing being tried anywhere ?