So someone in this thread or the other has probably mentioned this, but I was thinking.
There has been reasonable speculation about Dark Souls II being a prequel, involving an undead's pilgrimage to Lordran, also the directors mentioning wanting the "Skyrim crowd", not to mention the trailer itself focusing on snowy mountains. I was remembering the landscape all around you when you break out of the asylum at the beginning, before the crow takes you away, when you pan the camera all you can see all the way around is snowy mountain ranges.
Makes me wonder if a very large part of the game takes place in that area in particular. I'm sure they'll have a variety of landscapes, but even within a mountain range they could have valleys, caverns, lava, etc.
I haven't played Skyrim, but I know from screens it seems to have a fairly diverse selection of terrain, but when you I think of the game I do think of all those snowy screens and, of course, fighting dragons.