Single pilot airliner ops in the future are probably going to happen.
Let's consider future FTL's. A/C can now fly for 16+ hours. What of the future? Imagine a single pilot on board an automatic a/c crossing the world's oceans. Launch, enter oceanic airspace, engage autonomous automatics according to transit clearance and then go to sleep in a cockpit bunk. 5-6 hours later wake up and carry on. Using current split duty rules you could be on duty for an outrageous period. It would not be surprising, reflecting on past performance of XAA's & EASA, that FTL's are adjusted to match a/c performance and extended even more. With automatic a/c and cockpit bunks, hugely lengthy duty periods on ultra long-haul flights with single pilots might well be approved. What horrors.