Blizzard Teasing Possible Diablo III Expansion

We’re all aware of the fact that Diablo III wasn’t quite the hit that its predecessor was, right? Well, that’s not anything that can’t be fixed with an expansion, or at least Blizzard thinks so, as they’re teasing what seems like it will be the game’s first one.
A website recently popped up with the header “Reaper of Souls”, and quotes a passage from the Book of Tyrael. Specifically a line that reads “Death, at last, shall spread its wings over all.”
Now, of course this doesn’t necessarily mean it’s an expansion, but that’s seeming the most likely, considering the game’s reaching that age where the timing for one would be right. Then again, it is always fun to guess on the more wild side of things, so who’s going to bet on it being a new Diablo-themed MOBA? Anyone?