Many Latin (and later, 20th century) dictatorships had in common a limited number of power points (major economic/strategic geography) within the country. They were warlord, semi feudal, leaders who overpowered other warlords in the country. There was very limited democratic experience, with a one percent power/99% peasant structure. The USA is a far different situation. There are multiple, geographically dispersed, power points. There is a history of democratic process, and the goal was to increase the role of democracy (unlike the Latin nations, where any espousal of democracy was a wink, wink, nod towards it, while using it to gain/control power). In most of the colonies, there was a strong middle class.
A military dictatorship is possible. The number of circumstances necessary to see it succeed make it highly unlikely, in my opinion.