User blog comment:Primeramizery/What could Mayuri be working on in his lab?/@comment-4207271-20130709084205/@comment-11051098-20130712012113

As far as we could see, only Renji, Rukia and Byakuya were brought to the Soul King dimension to be healed. And if Mayuri is resurrecting someone, I rather think it's Unohana than Kira. She's tons better than him at both swordmanship and healing, she would be the logical choice to revive of the 2.

Maybe Kira was picked up and healed by one of the medical teams of the 4th Division. I'd say that's his only hope to survive.