Exactly how that may have played out in the last century could be explained by many, many chains of causes and effects. But it wasn't a great leader that made it happen. At the bottom of everything, I believe it was this:
Decades of Famine, Pestilence, War, and Death destroyed not only capital but huge swaths of the labor pool. With labor at a premium, it became more valuable and power shifted.
I think that without a similar apocalypse, it will not happen again.
Yes, economic disaster is the driver (tangential: a lump-of-labor supply shock was not the transmission mechanism), but big political movements always happen from the pieces lying around. Everyone can feel that a disaster of one form or another is coming. We need to make sure the right pieces are lying around.
Decades of Famine, Pestilence, War, and Death destroyed not only capital but huge swaths of the labor pool. With labor at a premium, it became more valuable and power shifted.
I think that without a similar apocalypse, it will not happen again.