Just a few ideas for future DLCs/patches:
-Further story regarding mage's guild and Eveyea - maybe introduce dealings with a new daedric prince (new, as in new to ESO), or conflict/partnership with psijics.
-Further story to Dark Brotherhood and/or Thieve's guild.
-Conflict between one or more: Dark Brotherhood, Morag Tong, the 3 alliances
-Something to do with one or more of the 9 divines, which has effects all over Tamriel. A grand story similar to the original main quest + Cadwell's silver/gold.
-Return of Molag Bal, maybe teamed up with another prince.
-A large story for all three of the Tribunal which has effects all over Tamriel.
-Etc.