Regime change is rare, but history is full of it. Aristotle posits that the order of regimes is monarchy into oligarchy into anarachy into monarchy, although this is obviously wrong as shown by Ceasar, Cromwell, etc.

The US does have a history of monarchs, which could also be characterized as constitutional executives, with Washington, Lincoln, and FDR. It's about time for another one, but any post-liberal regime will definitionally have to be more radical than any of the previous monarchically established iterations.