There's no inherently intractable reason aircraft "need" human pilots when autopilots are faster, better and make fewer errors. At this stage, an aircraft guider would be able to instruct the aircraft as to what's needed. At some point in the future, AI/ML/DL will replace that role entirely such that the lineman communicates with the aircraft directly. Then, as a further iteration (40-100 years), the lineman is also replaced by robotics on a drone-like platform.