In Oblivion. One of the most annoying things imo was that you couldn't be part of "The Mythic Dawn" because you always ended up killing Mankar Camoran. But I agree with the Oblivion invasion, Tamriel was Dagon's and Akatosh banished him. But it would have been cool if I ended up killing Martin.
And in Skyrim needs a deeper story. I mean seriously; the dragons awaken and start attacking everyone, you kill them and become Dovahkiin hero. That's not a very good story. But if the story does end up with a villain I would like to join him. I mean it would add so much more possibilities.

Take it easy there.

150 hours of scripted gameplay or 20 hours of a well thought out and choice dependent story line?

Take your pick.

Well, in Daggerfall there was several endings, and that ended in the warp in the west. I doubt we'll se something like THAT again.

Why would you want to help Alduin? He's going to, quite literally, EAT Nirn. If he wins its rocks fall everyone dies for the entire frigging plane(t). Now, I could see maybe picking sides during the civil war, but the main villain whether his morality is black and white or orange and blue, is a definite enemy to just about everyone that likes being alive.

It was like that in Daggerfall, it had multiple endings. You know how lore fixed it? Dragon Break, the Warp in the West. Sure it worked out, but if we're breaking these dragons every game the lore would get repetitive and become ultimately unrealistic.

You couldn't join Dagoth Ur in Morrowind either, so I don't see the problem.

Also the story will be more complex than "are you bad enough dude to kill all the dragons?", I mean there's a reason all these dragons are here.

And there's this civil war too. I've heard somewhere that you could choose which side you want to take in it so it won't be as linear as Oblivion hopefully.

the witcher?

They could add alternate paths, but with the same ending... and the same ending to the biggest events... I mean just because I choose to join the anti-imperial side of the civil war doesn't mean the imperial one has to lose...

althought the main story line i dont feel will have a choice for and alternate end.. i do feel that you may be able to choice you side in the civil war...
in oblivion an alternate ending would of been huge, you'd need to change the whole of Cyrodill to a ripped to pieces burn out wasteland, where there are no people apart from the few mythic dawn (possibly even though i believe he well and truly tricked mankar and was going to leave them trapped in that "paradise" place) also you'd need to create loads of daedra everywhere to run shops and things

That wouldnt make sense with the lore if there were completley different endings. If it was stand alone then it would be ok but its a series.

Not different endings, different paths to the same ending. The example the OP gave wasn't the best, but you can have similar endings with two different paths to get there. Think of the Bloodmoon main quest... you could side with Hircine or the Skaal, but the end of the quest still resulted in you beating Hircine's Hunt. Dragon Breaks need not apply.