It's coming folks, and you aren't going to stop it. Many underground systems are unmanned and work without incident. As someone said earlier Airbus have demonstrated an A350 gate to gate without anyone doing anything other than starting the engines. I can remember when folks said ETOPS was a bad thing and we'd have 1000's of hull losses. Autoland and autobrakes improved safety. The biggest air disasters have been caused when pilots did not follow instructions (Tenerife).
I totally get the 'what happens when' scenarios - engine failure, fire, a control surface detaching, non-retractable gear, etc. Many of these happen, and the outcome isn't always great with two skilled crew on board. I get the automated car analogy, but comparing that to aerospace is wrong. Automated cars have to deal with people, and people are unpredictable in their movements. Airspace there's separation and the systems will allow
For me, the biggest risk is the boredom faced by the solo pilot for 4 or 5 hours.