It's already happening. Imagine delivery of high-value, light goods to remote locations, e.g. medicines in the Australian Outback, or island off the German coast. These are examples of what has already been done.
http://defensetech.org/2011/12/21/marines-get-first-ever-res...
no need to imagine as there has already been successful POC of delivering Hellfire missiles into Yemen villages.
A drone can bypass all of that inefficiency and show up in my window 60 seconds after the meal is cooked. In New York it could deliver to the fire escape or to a special landing pads, or just hover in front of the 3rd window on the left on the 5th floor for 30 seconds.
What happens to the illegal delivery guy living on the tip is an entirely different question.
This future seems positively utopian
Not saying it's impossible, but I see tons of additional concerns, both practical and related to safety.
All these arguments against drones have very easy technological answers.
There is little safe space to fly over in cities - you can't just start flying over roads and pavements, because if any malfunction happens, you'll be dropping a 10kg high-velocity brick at people and cars. You'll need at least specialized insurance for that, and I'm not sure if anyone gives this kind of thing.
Edit - a good talk on some of the issues that might be faced with traditional delivery systems: https://www.ted.com/talks/andreas_raptopoulos_no_roads_there...