There's plenty of clues about what the Skyrim DLC may be about buried in some Skyrim patch filenames.
Dragon mounts, Morrowind, and Daedrics, oh my!
These are just a few of the wild rumors floating about on the Internet about what Skyrim's DLC could be about. However, a BethSoft forum user found some concrete evidence as to what the DLC's contents could actually be after scanning the Skyrim 1.5.26 patch files, revealing the following filenames (among others):
The patch file scan turned up other features as well, including what seems to be new vampire feeding animations and something mysteriously prefixed as "RF." However, what you should be caring about is the clear indicator that the DLC will include snow elves, the Snow Prince, and crossbows.
If you're not too familiar with the snow elves, perhaps the Falmers will help you jog your memory. Yes, I'm speaking of those terrifying, underground creatures you've probably encountered multiple times on your journey through Skyrim. Reading up on the lore of the Falmers, you'll discover that they were once snow elves led by the Snow Prince against the first humans on Tamriel, Nords from Atmora who had immigrated over.
The Snow Prince was eventually slain in battle. The rest of the snow elves, a weakened force, sought refuge with the Dwemers in Blackreach. The Dwemers agreed to shelter the snow elves, but didn't trust them, force feeding the snow elves toxic fungi that caused them to become blind. The snow elves became the Dwemers servants and over time, twisted into the Falmers that you see in Skyrim.
Will we be able to revisit this part of Elder Scrolls lore in the upcoming DLC? Or will we see something different entirely? There were plenty of hints dropped through Skyrim through the in-game text "The Falmer: A Study" that suggested that the Falmer were to return to the surface. It would definitely make for an interesting story arc to have the DLC be about fighting back the Falmer as they attempt to regain their past glory.
As for the crossbows, I just hope that Bethesda doesn't ground them too much into reality, or else reload times will be absolutely dismal.