As long as the Underworld franchise is making money, expect them to go right on making them. The last one grossed $91 million worldwide and cost only $35 million to make, so, here comes Underworld 4.

Shock Till You Drop confirms that Sony’s Screen Gems is moving forward on Underworld 4, and planning it for a January 2011 release. There’s a twist this time. Underworld 4 will be in 3-D.

So who will be in it? The first two movies starred Kate Beckinsale and Scott Speedman. In the third one Speedman was left out in the cold while Beckinsale was replaced (sort of) by her doppelganger Rhona Mitra. The only constants through all three movies have been Bill Nighy and Michael Sheen. Nighy as head vampire and Sheen as the occasionally tragic werewolf leader. There’s no official word yet on who they’ll rope into the fourth movie but it’s hard to imagine Beckinsale going back to it while on the other hand, Rhona Mitra isn’t particularly busy. I’m betting on Rhona. We’ll let you know when we know.