My guess is werewolves or, even better, lycanthropes.
My guess is based on the fact that a popular werewolf mod recently broke, and another site posted that the developer dropped out of the game. BUT the mod was last updated just this summer, so why did they suddenly stop updating and drop out of the game? It might just be coincidence, but I am guessing (and hoping) that they stopped working on the mod because EA bought it from them to use in one of their own expansions.
I think this would be cool, because I'm really into folklore. If they are doing this, I'm hoping it's lycanthropes, so they could add other wereanimals. I'd put werefoxes in Mt. Komorebi, a wereshark for Sulani, and a Norwegian werebear in Windenburg.