Data found by someone with a lot of spare time to read Skyrim's code following the last patch has found files named "DLC2" and "Dragonborn" but MUCH more importantly, they have found Dragon-riding animations, casting spells from mounts, quest markers for Solstheim, Telvanni, Castle Karstaag, Raven Rock, and Miraak Temple, and Bonemould, Chitin, Nord and Stalhrim armour varieties.