The only way a revolution would succeed would be if a fairly good sized prortion of the military sided with the revolutionaries. I could only see that happening if what the military was ordered to do violated the constitution in an egregious manner. It would probably require a bunch of general or flag officers in order to make that happen.
The military oath requires two things:
1. support and defend the constituion
2. obey the orders of the president and the officers appointed over you
I don't think the order of those two things in the oath is insignificant.