User blog comment:B214/High School DxD EX/@comment-50.139.232.230-20150728035746/@comment-4320546-20150802103456

That'd be impossible. Issei's already mentioned to still be alive in the future. Even if he wasn't Ichs doesn't have human blood at all (Issei now only has dragon and devil blood, Rias has devil blood), so he'd never get a Sacred Gear unless he went through a situation like Sairaorg.