Especcially if one hears the "experts" on the direction they expect the oil price to go in the next years. I have heard figures up to $400-500 a barrel within the next 5 years, so that would mean fuel economy will have a completely different meaning. Knowing that the taxes on fuel are often enough percentages, this could mean prices at the pump of $50-60 per USG automotive fuel in Europe with $100 per gallon of specified aviation fuels.
That would be when things stop happening. Jet Fuel however could never reach such abusive heights as it would kill the airline industry totally.
I don't think I could call the potential prices 'abusive' though. Jet-A1 is already untaxed in most of the world, so if the price of oil quintuples so will the price of Jet-A1 (more or less). I find it more abusive that you pay fuel duty if you take a long-distance train within the UK, but not the plane.
'Apocalyptic' doesn't mean 'impossible', and if the Chinese decide they like cars, and if the rumours about Saudi reserves are true, then this may come to pass.
At the few regional airports I've been to in the UK it's struck me that there are more multimillion $$$ private jets on the apron than there are AVGAS burners. Even if there are a few Jodels and cubs hidden in hangars, the Cessna Citations seem to fly more. I think it reflects the current massive wealth gap within our society.
My bet is that the people who have the ear of the government are more likely to be in the Citations than the cubs. I would wager that AVGAS is used primarily by people who are economically in the 90-99%iles - wealthy enough to be resented (middle grade bankers), but not rich enough to really matter to decision makers. I can't see leaded AVGAS winning many friends in politics - at least in the UK. I can't really speak for the US, but I wouldn't be surprised if the situation is similar there.