I believe that if such large-size electric flying drones could have just 15-20 minutes of autonomy, interesting applications would already become possible. If a flying vehicle could fly at 100 kilometers per hour, it would only need 5 minutes at cruise speed to fly me to downtown, assuming it's flying in a straight line. The scenario I have in mind goes something like this: you dial an app on your phone, within 4 minutes a flying drone pod shows up, flashes safety lights to signal its presence, and gently lands in front of your doorstep (or perhaps at a designated landing pad).