The only sequel that I see is if:
But even with that, it's not a terribly interesting sequel. Wiseman, the director in interviews this past week, seems more keen on doing a prequel than a sequel which I think has more potential because as Simon mentioned, they've taken this particular storyline as far as it can go. Selene knows the truth now and in a way has regained alot of what she lost because of this bloodfeud. She has love now and she's able to walk in the light now. I could see her and Michael living in a mountain cottage never to be heard from again.
If I were Wiseman, I'd end it here and not even do a prequel. What I would do is cut the two films together and see how it would work as one on DVD someday.