Depends on the type of drones you want to use and their range. Helicopter-like drones have very poor range and flight time, so this would limit your range considerably. And if you go to a plane-like drone, or even some kind of hybrid mode (eg. VTOL), suddenly you can't really do an emergency hover when cruising to destination.

But even if they find a way to handle the traffic, I was just saying that there will be traffic and that this poses serious problems.