The key to your argument is a “Determined Government”. A determined government must have a taste for the blood of the governed. The chances of us having a military willing to move against our people is tempered by the strength of our governors and their influence over the national guard. As a nation we are yet to large for central command and control and have sufficiently divided authority so as to make protecting one’s self from the government remains a second amendment issue.
Barack, Harry and company are working to fix that.
Given this thread from last year, the governors [in general] have zero strength when it comes to exercising their authority against the federal government. I mailed, via registered mail, nearly all the governors — of the replies that I got back most were of the this is a federal issue
strain.