How will the Reich collapse? Even if Smith secedes from the Greater Reich, he needs nukes, lot of them & some "rather" moderate Führer who dont just nukes America to kingdom come. In three seasons we didnt see one resistance cell outside of America or any meaningful opposition to the Reich. The only way I can see the Reich breaks up is in a Alexander the Great successors states kind of way. Some Gauleiters make their own petty little Empires, but still adhere to the shared Nazi culture.