User blog comment:Xilinoc/Ch. 586 - The Headless Star 5/@comment-11506376-20140625171259/@comment-24306779-20140626165940

Well, in fact Kanae Katagiri died three months after Auswählen, so it's not impossible for As to have survived. I think the fact that Yhwach says "So you're one of the survivors" points towards that theory since there isn't any other major event he could be referring to.