They discovered another DLC that's referenced as 'DLC2' and 'Dragonborn'. Apparently dragon mounts are coming, as well as a trip outside of Skyrim to the lands of Morrowind?
The game's updated filespack from Bethesda. Within the files it mentions 'DragonMounted' text files, which all look to support the new mounted combat.
There are also quests mentioned in locations such as Solstheim, Telvanni, Castle Karstaag, Raven Rock and Miraak Temple. Solstheim is east of Skyrim and bordering Morrowind. Bethesda's parent company Zenimax recently trademarked 'Dragonborn' for DLC content purposes. Flying dragons to ride to town? Yes, please.