Still though, it's years away from implementation and there are some obvious drawbacks and limitations, such as:
-battery life of drone
-costs of operating the drone (manned/unmanned)
-how does the drone distinguish dropping the package at you doorstep or at the front of your driveway?
-cannot deliver to apartments/condos
-delivery has to be within a distribution centre
I think this is all just a concept - no different than working concept cars that car manufacturers bring out on auto shows