Thinking about it I can see the pressure coming from 3 directions:-
1. The military are already looking at drones/unmanned aircraft to deliver supplies over significant distances - that will no doubt include R&D against hacking...... and if they can do it?
2. Amazon etc are looking at delivery by drones - so that leads to scaling up - packages, then van loads, then truck loads......
3. Airline management want a more uniform, controled and lower cost operation
It's going to happen I think - and maybe sooner than we expect......... after Mr B introduces the MoMA it's going to be hard for airframers/engine manufacturers to keep reducing costs by 15% per design iteration and single manned/unmanned will be an obvious way forward