Even if it is feasable in the next few years, I can't see it being rolled out universally, as it couldn't work for everyone.
How would you deliver to an address in an block of flats/apartments etc. for example?
With restrictions to delivery addresses, or location restrictions due to security or safety reasons, it would only be possible to deliver to selected addresses, and not to everyone.
It may well have a place, but it looks more of a gimmic than actually practical.
I'd imagine the aviation authorities, and the police and security services having something to say on the matter too.