The Skyrim dungeon experience boils down to following a path, fighting some bandits/monsters/Draugrs, and then finding some treasure and the exit door. Not only were the dungeons in Skyrim fairly linear experiences, they weren’t even all that hard to complete. Whatever the new content for Skyrim is, we hope to see some more variation in not just how we traverse through a dungeon, but in how challenging they are as well.
One way to make dungeons tougher is to merely make them darker. How many caves in Skyrim were almost perfectly lit? There was almost no reason to use illumination spells in the game at all. By making dungeons darker, not only does it make it tougher for players to get around, but it also makes enemies in the dungeons aware of where you are.
As for making the exploration more diverse, all that’s needed is a few branching paths. Dungeons would be infinitely more interesting if we had to deviate from the single passageway guiding our character through to the other side. Throw in some more puzzle elements besides the tired fish/snake/bird stones, and we’d be happy.