User blog comment:Mnzombie/Issei's Peerage/@comment-23853100-20131107025909/@comment-92.40.249.178-20140106153955

Well the author hasn't said that the current arc is the last one, and he once said that he has a Indra arc so there is still quite a bit of life left. Also Issei Kiba and Akeno are already mid-class and Rias has yet to even graduate so my guess is that the arcs are about Issei and his peerage along with Rias' peerage.