That's kind of the point though, even if the army and police didn't revolt, they're crippled by the lack of services produced by the civilians. Major upheaval like this hypothetical have multiple times in history crippled even the most well equipped amred forces because of the nature of the revolt. Guns are only 1 part of defence, and every time there has been a populace under the rule of a government/system that they refuse to exist under it has either been overthrown or in the process of being so. This is an easily verified fact by looking through history, governance requires at least a majority of the populace to consent to it.