User blog comment:Swordbirth18/Possibilities for highschool dxd season 4/@comment-1359322-20160708113030

https://twitter.com/ishibumi_ddd/status/750923944677351424

From Ishibumi's twitter. He didn't make things clear but he placed a #haremking which is something the anime used. So there's a possibility of an upcoming anime-related project. Whether or not it is season 4 remains to be known. It could be another OVA for all we know.