When speaking with GGN Gamer, Dark Souls director Hidetaka Miyazaki announced that the studio is already working on a brand new IP, saying "Dark Souls is over" and "development of a new IP has already begun."
This isn't a brand-new revelation by any means. Previously Miyazaki had announced that Dark Souls 3 would be the final game in the series, so fans have had time to come to terms. In previous interviews he's also expressed the desire to move on and "try new things." But despite his seemingly black and white statement about the series' future, he's not averse to returning to it at some point.
"There's absolutely no plan right now for any sequels, spin-offs or tie-ins. But I can't say for certain the possibility is zero percent," he explained, stressing that what's "certain for now" is that to him personally that Dark Souls is over.
As far as support for Dark Souls 3, however, Miyazaki did confirm that two additional DLC packs will be available later this year and early 2017. The Dark Souls franchise may have drawn to a close for now, but it's certainly ripe for a return for some easy money five years down the road.