While I think it will eventually come to single pilot/pilotless aircraft, it won't happen in my lifetime. Two major roadblocks still remain and neither are certification or technology orientated. With the projection of the need for 500k+ more skilled pilots in the next 20 years at the airline level globally, I seriously doubt the top global pilot unions will sit idle and let "technology" cut those dues paying numbers by half or to zero. Their combined clout politically and economically will make single-pilot 121 pax ops very difficult. Cargo perhaps in a shorter time period but not pax ops. But the biggest hurdle is the insurance side of things. With dozens of pilot incapacitations every year for various reasons recorded worldwide, I also doubt there are no insurance companies willing to take that risk on a single pilot cockpit. And neither would I given the first hand experiences I've had on the maintenance side of chasing phantom system tech faults that only need the battery discounted for 5 mins to fix. So until the tech side can develop a 100% defect free system I doubt any insurance underwriter will write a policy on a pax carrying A350 with a single pilot. As to the certification side, I think it is moot as economics will drive that change just as it has with drones, LSA, regulatory rewrites, etc. and as historical record has shown us.