User blog comment:Salubri/Gotei 13 vs. Wandenreich: War So Far/@comment-4207271-20140427053442/@comment-1387259-20140427065722

Well, Isane was able to confirm they were dead, but we also gained a better understanding of Gremmy's abilities since then. So I'd say it's possible they're still kicking or can be "brought back" in some manner.