I'm beginning to favor the Stormcloaks efforts to succede for this reason: If Skyrim leaves the Empire, Skyrim will likely ally itself with Hammerfell, and with those two powerful provinces allied, many other smaller provinces, seeing their power, will likely join their alliance and leave the Empire, which would obviously destroy the Empire. The Geat War II would be fought and in the end the provinces would simply go about their own business, and each would try to keep the peace with eachother. Even if you side with the Empire, the provinces will likely leave in the after math of the Great War II, and Tamriel would become as it was before Talos came along. Its possible a new Empire would arise with Skyrim or Hammerfell at the head, more or less an alliance of provinces with the most powerful leading them. Cyrodil is out of the question as no one would want the Imperials leading them again.
I'm seeing this whole thing as the Empire's last grasp to hold on to its power, which its losing rapidly. I myself have no intention to help it pull its self out of the hole its dug itself into. Maybe its time for a new stronger Empire or Alliance of provinces to be forged out of the burning embers of that last Empire. People may say the Empire needs Skyrim to beat the Thalmor, but with Skyrim and Hammerfell combined I think they dont need the Empire anymore, seeing as how a ragtag group of guerilla fighters can beat the Imperial Legion while being outnumbered and under equiped, and Hammerfell can hold back the might of the Thalmor alone when it was abandoned by the Empire. I'm still not sure as who to support in the Civil War, but I'm leaning heavily to the Stormcloaks, seeing what a Tamriel would be without the current Empire. Empires rise and fall, and sometimes stronger Empires are forged out of the remnants of the last.