I am with Denti, the operating cost of two pilots is fairly small, compared to general operating costs. On the other hand, the cost of development and verification of an autonomous control system is very high. UAVs have an operator, who directs the vehicle during its mission.
I think Cruise Missiles can truly be called autonomic vehicles... but their control systems only needed to be validated against "has a decent chance of completing a suicide mission", which is not exactly the standard that an airline passenger expects.
I expect that there will be progress in the area of autonomous vehicles, both land-based and airborne; but for planes I expect to see them first in military and GA (patrol, crop dusting) applications; it will take a long time before we will see autonomous airliners.