I would expect that we will soon see petrol powered drones (IC engines)
A IC engined drone does not need to be the same weight as a conventional Helicopter because of the different technology that they use
The same as electric cars, unless they produce a vastly superior battery the size, range and speed will severely limit them unless they return to a IC engine
IMHO the "pizza delivery drone" is only an advertising gimmick as they can't possible have 40 or 50 drones in the air around each Pizza shop at the same time
As mentioned with the Chinese drone it has the ability to fly between buildings and they already have the capacity to alter course to go around other objects automatically
