To be fair, the technology sigmoid curve rises fastest just before its inflection point, so it is hard to predict at what point innovation slows down due to its very nature.

The first Boeing 747 was rolled out in 1968, only 65 years after the first successful heavier-than-air flight. If you told people back then that not much will fundamentally change in civil aviation over the next 57 years, no one would have believed you.