User blog comment:B214/Volume 23 discussion blog/@comment-172.56.17.58-20170417051436/@comment-1359322-20170419142652

Except Sairaorg is a pure Devil. Ise is not. Regardless of Ise's status that doesn't change. And we're already handed the information and knowledge of what happens when your clan no longer has a Pure-blooded Devil in them. They are classify as extinct.

Also Millicas is already confirmed to be next in line so he already is the rightful heir. Same for Rias, she is a rightful heiress chosen by her parents.