If we think about this from a development perspective they need things to finish up in such a way that it will all head one direction no matter what side we as players choose. and example of this would be the Civil war: you have to choose the empire or the stormcloaks. after it all you think to yourself "what ending is cannon?"

solution to this being something to the effect of:
-if you side with the stormcloaks and defeat the empire they simply come back under a new general, together you throw the Thalmor out of skyirm and somewere along the line ulfric is killed in battle

-if you side with the empire the stormcloak rebelion builds up under another leader, and together you throw the thalmor out of skyrim and somewere along the line tulius is killed in battle

tada, no matter what we decided in the Civil War questline we get the same outcome with the same two new representitives for the Stormclaoks and the Empire, who i hope would be more reasonable and work together.

I am asuming we will will have at least one more big DLC that does tie up the civil war and the state of skyrim together. these sort of things are usually saved for the last DLC. besides, there is no happy ending and i find it rather anoying. i require one nice big DLC that has us all rally together and throw the Thalmor out of skyrim and spark another great war. . .that we will win.