Surely ATC would be another hurdle unless every other aircraft is also pilotless?
I'm thinking there will be a lot of unforseen job creation in order to service/maintain, ensure certification/compliance of systems, troubleshoot errors and deal with the excessive amount of new red tape that will come with completely pilotless aircraft. Have the cost savings been fully understood?
Single pilot could be all it comes to in 20 years time, and it will be trialled in cargo operations first no doubt.
Driverless trains and cars can roll to a stop or have a low speed collision (best case scenario). But hey, maybe ballistic parachutes will be attached to large jets to allow a "safe" way to crash
This is still in it's infancy