It would make for a nice piece of fiction: a book about a post-2A repeal United States where the government battles its armed citizenry, prying gun after gun from cold hands, until there are no longer any armed authorities left prying guns.
True. What leads up to that is a far more interesting read. Matthew Bracken ('Travis McGee' on FR) wrote Enemies Foreign & Domestic. You should check it out. A very good read.
BTW, he sort of covered the scenario you outlined in his subsequent novels, Domestic Enemies: The Reconquista and Foreign Enemies & Traitors.