Should be adapted? Nay, they will absolutely need to be adapted, at least for an mmo version of Skyrim. There are plenty of required quest-related NPCs that are killed or just go away in the normal progression of the game. It would probably be easier to scrap the vanilla quests altogether, and just include generic go-kill-enemy-X-at-cave-Y missions. Yes, you are right. Well not each and every quest! But just killing an enemy will become boring. I am sure creative people could come up with quests that are more than fetching NPCs which will also be fun for a group of people. Although I am sure the majority will make do with massive battle fields, fighting against each other in Skyrim.