I find it highly unlikely that Skyrim will be as large as it is supposed to be in lore, considering the work that would involve. And I really wouldn't want it either, as that would likely come at a large sacrifice in the detail, variety and quality of the game's content, and I've already felt that Oblivion was not varied enough, I somehow doubt making it on Daggerfall's scale would improve that, no matter what kind of technology Bethesda has access to. But it may be that the map can safely be bigger than Cyrodiil without sacrificing too much in the way of quality. If this can be done, I'd say it would be the best approach. In the end, I don't mind if the map is somewhat smaller than it should be in lore, provided that it's large enough to provide enough content to keep me interested, and large enough to create an illusion that it's of a somewhat believable size.
For skyrim to be set to scale it would have to be the largest videogame world of all time. Sorry.
Actually, I wouldn't be so sure of that, it would certainly be the largest game world on the market, I'm sure, but would it be larger than Daggerfall?