There's only so much oil, it will eventually run out even if we suck the Earth dry of every last drop, so if there's not an alternative, there'll be a population crash.
Plus, was religious and ideological fundamentalism exploding worldwide in the 70's? I really have no idea, but fundamentalist lunacy seems to be part of the current zeitgeist, and adding that to any equation just makes it that much more unstable.
Only so much oil...that could be a direct quote from the '70s. There was a commercial running then with a dinosaur going extinct that said the same thing. Everyone was looking for alternative fuel sources and cutting back oil consumption. Then, oil was found in Saudi, end of crisis....only it shouldn't have been. Just because we didn't have to worry right at that moment about any shortages it was still eventually going to run out.
You misread my post a bit - I didn't say future fuel was gasoline. It's just that whatever is it is, I guarantee it won't be worry free.