The aircraft in question are already highly autonomous with Auto TCAS and Auto emergency descent. Autonomous taxi trials are underway at Toulouse, and these flights have already been conducted, with the only real pilot input being altering the FCU, and a TCAS and visual lookout. Except as stated through Russian airspace ( when we used it ) due to lack of CPDLC and the PRC, due to terrain and paranoid standards of control that can’t help but interfere all the time. Albeit with a full crew available and rotated through as required. However that is more of a requirement for the entire crew to witness the operation as opposed to fatigue.
As to VHF outages a fair part of the world has CPDLC coverage, satellite enabled. I can’t remember when I last had a prolonged comms outage, even in the Dark Continent.
Incapacitation is a factor. That’ll be down to the regulators and our excellent (!) medicals. Likely to get more stringent and more invasive. A bigger factor is the chance of a “Eurowings” type event and indeed the effect on the mental health of the pilots involved due to isolation etc. That said, carriers in the less enlightened parts of the world have been quite happy to have their crews confined to their hotel rooms on layover with little or no interaction for almost 2 years now, consigned to endless loop rostering, with the only way out to the greater community and your families to spend a further 14, or 21 days locked up in a hotel at the end of the loop. And endless cycles of pointless testing.
So, it is being actively looked at. With the initial aim to reduce crews from 4 to 3, 3 to 2 etc etc. A beancounters wet dream.
Convince yourself that this is 30 years away if you wish.