User blog comment:Jopjopjop/Volume 20 Spoilers/@comment-73.157.117.201-20150728114735/@comment-26285797-20150728131002

I hope so, too. But since there are no more planned power-ups, tenatively, I would say if DxD goes on, it is only going to be brief. Yes, there are several avenues to travel, and, yes, a Volume 22 is more than guaranteed seeing as Vali and Issei are going to be busy fighting off 666 next one, but I believe that we're at the close. We've seen Issei grow to what Ishibumi believes to be the final stage of his evolution, so I doubt we'll see too much more. But I am hoping for more. One thought to consider is that Ishibumi could throw a final power-up into the fray for both Issei and Vali, and, as you said, the DxD world can be further explored considering the way it was created.