I was at a RAeS event recently where this was being discussed. One presenter, an engineer was enthusiastically proposing that pilotless airliners would be here in 20 years. I disagreed, and when asked why, I pointed out that as a pilot, I consider that only about 5% of my flights proceed as planned without requiring some form of intervention. I fly in a high threat environment with long periods of poor weather, high terrain, less than sparkling ATC, political issues and a high number of passenger handling problems. Nearly all my flights require me to apply my considerable experience and presence on the flight deck to resolve.
And not forgetting that the EICAS/ECAM procedures are an engineers best guess at the problem. In my experience, rarely do they work as planned. In the last four big events I have had in the last five years on Airbus types, none of the ECAM procedures correctly dealt with the actual problem. The last one would have had us depressurising the aircraft had we followed the EACM procedures. The solution came from our technical knowledge of the aircraft and analysis of the actual problem.
Of course, these issues could be resolved with more computing power and more procedures. But if this were to happen, any pilotless airliner will have to have to be equipped with artificial intelligence which would have to apply a variable risk assessment factor to resolve any problems. This may even have to ignore inputs from ground control sources if 'thought' inappropriate. I reckon it's going to be a long time before that level of AI becomes available, and even longer before manufacturers, regulators and insurers are willing to endorse that. Let alone the fare paying public accepting it!
One question asked was "Would you get in a self flying airliner?" My answer was that I wouldn't have to as I consider that they are at least 40 years away and my passenger flying days would be over by then, if still alive.