Something original, pherphaps? Not Werewolves or Werebears. Something completely not thought-of and new. That's what Beth and Skyrim needs, something new...
I'm afraid to say we probably won't see that, at least in this area. If any form of werecreature appears in the game at all, it's probably going to be one we've all seen before, my guess is werewolves, if any at all, and MAYBE werebears.
Now on this subject, I'd say that, if it's a relevant question at all, then probably getting infected with one disease should prevent you from getting the other, and the thing is likely true for lycanthropy and vampirism. Though more likely, only one kind of werecreature appears, if we see any at all.