User blog comment:Striker10/High School DxD BorN episode 7 review/@comment-26285797-20150518163502/@comment-24502975-20150519154255

I'd also expect S4 to include a lot of missed content from BorN. There's also the possibility for a 2-cour if TNK makes enough money and doesn't adapt anything else in between.

They definitely have plans for S4 though, that much you can be sure of.