Sealed flight deck doors are a non starter. Even the cost of supplying basic amenities such as galley and loo and leg stretch area, yes pilots suffer from DVT as well. But will airlines / the paying passenger be prepared to pay for the third pilot on every flight. Who else is going to tighten the harness and pull the incapacitated pilot clear of the controls?
So it looks like we have to have sky marshalls and three crew on every flight.
Low cost airlines?????