<sarcasm>
Cost of specialized drone wherehouse in remote England: $1.2mm
Cost of 3+yrs of R&D of drone fleet: $436mm
Cost of delivering first package: priceless
</sarcasm>
I'm not sure how this is ever going to compare with a truck and driver, especially when the truck will be self-driving in less than a decade.
Or...better yet, there would be a self-driving truck/flat-bed which drives close to a certain city-center area, and has on its bed a mini-fleet of drones, these drones will lift-off from the truck instead of the fulfillment hub...these smaller drones would deliver it to the front door. Alternatively, the self-driving truck could have a cartoon-like robotic arm that extends to the customer's front door; ringing the doorbell automatically and dropping the package on the doormat. ;-)
I'm not sure how this is ever going to compare with a truck and driver, especially when the truck will be self-driving in less than a decade.