Bethesda has teased more upcoming Dishonored content with a pair of mysterious images posted on its blog, with the promise of more to come. In the previous DLC, The Knife of Dunwall, the assassin Daud encountered a witch named Delilah who is part of a coven dubbed The Brigmore Witches. I felt the DLC ended somewhat abruptly, so it wouldn't surprise me if the story continued in an upcoming update.
Whilst there's no official confirmation, an entry on the Dishonored Wiki points to The Witches of Brigmore as being the title of the next DLC pack and the conclusion of Daud's story. Whilst I'd be very happy with a full-blown sequel being announced, I'm fine with another DLC pack for the time being. At any rate, we'll know tomorrow what Bethesda has up its sleeve.