We can hope... although by the sounds of it the Dawnguard will have a troll butler.
It may just be like the DB Sanctuary where you add a few things.. or possibly a bit more fleshed out, where you can change the actual Asthetics of the castle... perhaps even have to defend from a VL attack or two, would make a good addition to the radiant quests
If the castle is big as in the screenshots, it would be nice to have a lot to customize maybe even more than "Battlehorn castle" of oblivion.
Yes some random Vamp attack each two weeks or a random vampire lair to destroy each month would be nice.