Massive Amazon warehouses
This is a major threat to us. Once they finish building warehouses, there wont be near as much need for moving freight by air. The freight will be stored in these massive warehouses in strategic locations around each US city. Not moved by airplanes but by trucks at a fraction of the cost. Can they house everything that one needs overnight ? No I dont think so. Can they house 60 percent of what they need. Probably. In any case I see this as a huge threat. International is a different story.