Via The Seattle Times:

…an Amazon patent document published in April: flying warehouses held aloft by blimps.

It would float above a city at 45,000 feet of height, and hold not only thousands of items, but a fleet of drones.

Gravity would make the drones more energy efficient, as they wouldn’t have to power up until they’re close to the ground.

The drones could make their way back to the mothership in a shuttle, accompanied by packages and workers not afraid of heights. It could move to hover over other cities based on demand.

That futuristic vision is preceded by a discussion of Amazon’s Voltron-like drone patent.