User blog comment:B214/High School DxD EX/@comment-201.239.133.207-20170104020556/@comment-30924344-20170105011900

Unless EX grows up to an age suitable to be head and Millicas hasn't had any children yet, then EX can be the next Head of the House. Sirzechs didn't have Millicas until like 84 years later so EX does have a high chance.