Lots of good info in all these comments but no one really knows yet. I’m sure they will pin it down. However a few comments noted the auto throttles will reduce power and bring the aircraft to an altitude 10,000 - 15,000 ft and allow pilot recovery from hypoxia.
But what is the result of a pilot suffering hypoxia for 2+ hours? Can you just snap out of it once you get a normal supply of oxygen or is there brain damage?