No doubt the radio operators, navigators and flight engineers at their respective times were sure aircraft will not fly without them just because of complication of the job they have been doing.
Trains without stockers? Cars without personal mechanics? Oh wait...
It costs over 25 million euros to man the cockpit over the average lifespan of narrobody jet. This is half of the brand new aircraft price. You may complain that ATC automation still not there? Because airlines are not interested. Now, if they will be given a chance to save 25m per aircraft, systems will do a magic leap in no time