So I very much hope it is just about vampires which is probably the case since most of the released info is dealing with vampire stuff.
It's ok if you hope so, and I too hope that the vampire lord is going to be epic, not to mention that I hope he looks different from his game jam video self. That the dlc is going to be solely about Vampires is unlikely though, at least judging by the files found in the patches.
If you look at the complete list of files that were found (more than 120 files), you will see, that there is only a total of 7 files mentioning vampires and 3 for coffins (including a coffin puzzle), while there are also 11 animation files for the snow elf prince, and 3 for a child crying. The child crying is very likely Falmer related, since we have seen concept art of a Falmer leader holding a human baby, and as has been mentioned a concept art about how the Falmer immitate children crying. So there are already 14 files related to the Falmer as well. So unless the Falmer
are vampires, and it's all the same, there will be other stuff included in this dlc.
There are also files mentioning the elder scroll. There are so many possibilities, maybe we get to see glimpses the past again? Or do we use it for something else entirely this time?
Animations\DLC01\IdleReadElderScrollEnd.HKXAnimations\DLC01\IdleReadElderScrollEnter.HKXAnimations\DLC01\IdleReadElderScrollLooping.HKXCan't wait for E3, seriously.