Board Thread:Questions and Answers/@comment-9826910-20130618064245/@comment-9826910-20130619202424

So, since his Hollow and Shinigami powers were awakened in tandem, they merged into one being where they wouldn't have any other way?

I'm not certain if he would gain a new, different spirit. It could simply become a fusion of the two, similar to how they fused to teach him the Final Getsuga Tenshou, or it could not have a spirit as Ichigo claims that he and his sword are one, which could imply that the spirits merged with him. Or they may just remain separate but equal parts of Zangetsu, with the larger blade the "real" Zangetsu, and the smaller blade the "old man".