You're seriously overstating the issue. CD Project with the first Witcher game offered 3 very different endings, and none ultimately had grievous impact on the following game. The same counts for a likely TES 6. I mean, seriously, just consider the time skips involved. It's been 200 years between Oblivion and Skyrim! With enough time in between you can explain anything away. Hell, you don't even need much time! Take this: Ulfric and the Stormcloaks win, but soon people realize what an egotistical and racist ass he really is. Three years after ascending to the throne, he's murdered in his sleep. Variations of that theme for imperials and Nord alike. You may be Dragonborn, but you can't stop human treachery and desires everywhere.