You never know, it could be they gave us DMC3 SE with the same storyline for Vergil as DMC3 cos they're working long and hard to incorporate all the mentioned characters in some capacity, may it just be cameo roles or full fledged storylines.
Cos it'll be roughly two years since the last installment, but that could just be purely due to the fact that the PS3 is so hard to develop for, simply cos the technology is so new and complicated for developers to get their heads around. But Im hopin that most characters are involved, minus Lady and Arkham, they've never had much use in my eyes.