Is the US ripe for a coup?

[Ravenshire]

Not at all. The German officer corps followed the Prussian school, and an oath (like the one they swore to Hitler personally) was beyond sacred to them. I swore an oath to defend the Constitution of the United States against all enemies, foreign and domestic. There is a difference there.

(emphasis is mine)

This is the loophole that I think could be used in the very unlikely event of a coup. If enough of the military became convinced the Trumpster was a legitimate domestic threat, and Congress had taken no action, they would be bound by their oath to defend their nation against that threat. This would most likely not take the form of action against the presidency, but action against the sitting president. It would also be a last ditch action in a case where congress has failed in their duty to a degree I find, despite all the corrupt fuck-nuggets currently elected, unbelievable.