The lead dev for the series (Itsuno) left Capcom about a year ago, so the series (at least as far as the games go) is probably on ice at the moment aside from the anime and crossovers that theyve been doing. That said, Kamiya (the original lead dev that worked on DMC1) returned to them, so maybe he picks the series back up.
Correction: Kamiya isnt exactly back with Capcom, its just the studio he owns now is working with Capcom to make an Okami sequel. Though he could probably do the same with DMC.