Personally, while I feel like werewolves could be interesting, I don't feel like they're the necessity people seem to think they are. A vampire doesn't need a werewolf to be interesting, it just needs an interesting story and good lore. Now, that said, there -are- the Frostmane to consider, some of which were said to be wolflike in appearance. It's very possible that werewolf myths and legends spawned from the sightings of such creatures, even if they are not, in a technical sense, werewolves. The presence of ACTUAL werewolves coupled with the lupine Frostmane would make for a sort of weird comparison. What would set them apart, really?