It's like an automated assembly line in 3 dimensions operated by robots. Humans monitor from distant points and decide a few issues but most of it is automated. These are already very safe systems and they have been in use for decades in manufacturing. The more difficult challenge will be integrating our automated (drone) aircraft with old-school human-driven craft, and the latter must stay in place for the forseeable future. It is a difficult challenge because people do not like being driven around by machines and probably never will, even though in time the drones will be equally safe. And if human pilots must be used for some aircraft, it becomes difficult to integrate the two types of airborne vehicle.

It is easy to predict a two-tiered system will evolve where drones do everything on one side of an airport while the second side operates where (for a price) you can still get human pilots. The two systems will be separate in which runways they use, but the difference may be as small as having separate runways for the two users. We are already rapidly getting the point of automated ground control at airports now and it is not a stretch to see drone traffic working alongside human aircraft. I tend to think however that some degree of separation will remain for a very long time, we will probably not see total integration during our lifetimes nor those of our children.