I know that theirs probably not going to be vampires but a crossbow would still be a great addition to the game. To be fair it was one of the main reasons why people got dawnguard and it would make the game better than just having a bow.overall it would be good to see the crossbow come back from dawnguard.
there will be crossbows also
there will be crossbows also im pretty sure there will be vampires... not sure why, just guessing it may have something to do with Morrowind having the whole vampire thing.
There are actually three
There are actually three clans of Vampires in Morrowind: the Berne, the Aundae (who seem to have ties with the Great House Dres) and the Quarra. They hate each other. I don't remember them to have a specific weakness to crossbows, though.
Just because the Dawnguard
Just because the Dawnguard used crossbows does not mean that vampire hunters have a monopoly on them, nor does it mean that vampires are particularly weak to them. Crossbows are mass produced by the Imperial Legion based on the original Dwemer design, which can also be founds in Morrowind.

There are already crossbows
There are already crossbows in Morrowind.