As people, we are often blindsided. Supply of oil is not the problem for aviation. Look at algae. It will power not only the many thirsty engines of the world, but feed cattle!
What is it that could derail aviation in a big way, then?
World markets are wedging into a technical pattern that will result in the terminal destruction, at least in the short and medium terms, of investor confidence the likes of which will be worse than that experienced in the depths of 2008/2009.
This is what will derail aviation.
The world will not need 1 million pilots simply because the demand for pilots will not be there. Sounds ominous, and doubtless brings the rain of condemnation on my head. But it is what it is, which is very bearish.
To look East for succour is folly, for China, India, Brazil et al have not delinked from the main game, that being the United States of America which, lamentably, is in ruin.
The next 20 years is what this thread is about.
In a word, it will be very 'challenging'.