I personally think more open world would be nice, but then again I could be thinking that because we've had no new open world (other then the wolves den) since launch - I may be wrong on that, though.

Personally dependent on how much they're going to add in the expansion I'm in no hurry to see anymore new areas. But maybe in the future they could implement new area's to accompany new dungeons, obviously, not for every new dungeon they introduce but just a small area that fits in nicely with the lore of the dungeon.