According to an interview with the man behind Street Fighter IV, Yoshinori Ono, at EventsHubs - Capcom won't greenlight sequels to games that hasn't been selling at least two million copies and that probably means no more Darkstalkers:
"We won't be releasing a new installment in the Darkstalkers series anytime soon. As we didn't manage to hit our sales targets for Darkstalkers Resurrection... so..."
Ono continues by explaining how things work over there:
"...at the end of the day, there are just some brick walls that a salaryman can never overcome *laughs*. For instance, if a game doesn't sell over 2 million copies, then we'd have to put the brakes on any plans for a sequel. All that means is that we weren't capable enough. And all we can do after that is to reflect on the experience, take what we can learn from it, and try to apply those lessons on some other title."
This might also mean we've seen the last of Lost Planet since the third game didn't even reach a million. DMC Devil May Cry did 1.6 million and hasn't gotten a proper sequel either and Dragon's Dogma reached 1.3 million - and there are no more games in that series announced either.