I think Lower Saxony could easily fall for a revolution, being a industrialized area and so on...
Brandenburg would probably be dominated by Prussian Junkers and nationalists. Then Lower Saxony and Brandenburg would present very different alternatives, both would seek to unite Germany. The Bavarians would first be upset, but could comet to like being "better Germans" and a Catholic Nation. They'd probably work together with the Austrians. The Rhine Germans would be pissed of and be divided in pro- French and anti- French camps. The pro- French camp would support French military presence and support the Rhineland as the democratic Germany, the ant- French faction would yell that French military presence stop reunification. The East Prussians would be pissed of since their nation didn't even last a year before the Poles conquered and annexed it.