That works for me. He has and/or learns the means to take out all types of supernatural enemies. That would keep his stories fresh and not just having one type of enemy. If you think about it, even when was just vampires as his enemy, the writer could have had the vampire rulers have other supernatural things working for and serving them. Things like werewolves, witches and other beings. They may have done so in the past, I just have not read it.