With the advancement of technology it's harder and harder to sympathize with the idea that firearms in the US could effectively combat governmental tyranny. Situations such as Ruby Ridge and Waco could be handled by drones now. It's hard to believe that there is a principle at play here deeper than a simple love of guns.
But realistically i can't even imagine USA going to war with any major trading partner, much less their own population.
More likely is some corrupt local city government gets ousted by organized people defecting to neighboring towns... again neighboring towns have police / weapons. But you can also just sue cities in state / federal court probably, as they don't have sovereignty. Not to mention elections. So again, i don't really see cities doing anything too stupid to a majority of their own population...
i think the need for weapons will continue to decrease as time goes on and the world economy consolidates more and more... weapons are mostly for sport, just like boxing or mma. Its more of a staged drama...