If what I've read about the Russian Empire just before the revolutions of 1917 is correct, then at least one was toppled pretty much by itself. But Voltaire said that power was a staircase with boots going up and slippers coming down, so Russia was probably not the only example.
However, that's government -- a noxious, parasitical, endemic social disease. What about the replacement of whole cultural systems, as with the success of Christianity and of capitalism? These did not take place as coups d'état; the coups, revolutions and wars occurred after they had pretty much succeeded on lower social levels.