That would be pretty unprecedented in TES series. Generally, you're told who the villain is from the very beginning, and it doesn't change at all.

That's why I want them to put a lot of effort into making Alduin a great and memorable opponent. If you aren't going to have any twists, you lose the element of surprise, but it also means you have the whole story to develop the villain into a character players will love to hate.

I actually Liked Mankar Camoran, he wasn't just doing what he was for the sake of being evil, he actually believed that he was doing the right thing by opening the Oblivion Gates, his misguided views on the Mundus and Lorkhan and all that made him feel like a more grey villian, he felt that he was helping Tamriel by rejoining it with Oblivion.

As for Dragons, I'll have to reserve judgement for when I play Skyrim.

Personally, I don't think the dragons are the actual villans in Skyrim. I think we will learn who the villan is when we learn why the dragons are back. I think it will play along the same lines as MW and OB where it is a specific group who brought them back...maybe to try and aid one side of the civil war and things got out of thier control.

I hope that Alduin or whoever is the 'big boss' is not just 'evil', but more something like Dagoth Ur. He was a well fleshed out character with interesting motives. On top of that you had the Tribunal, who presented themselves as the 'good guys' but when you find out more about them you'll understand that they're not all that good.

Moral ambiguity FTW.