Board Thread:General Discussion/@comment-24472198-20140127004340/@comment-11051098-20140127181438

His Bankai and skills with Kidô, Shunpô and the tricks he learned from Yoruichi makes him a very skilled opponent. It would be a great loss to the Gotei 13 to lose Byakuya, IMO.

It could have gone that way, cos after all, he was really run through the grinder with his own Bankai. Out of logic, I would say it appears that he just barely escaped death.