Board Thread:Theories and Speculation/@comment-35205005-20180406164902/@comment-4974066-20180406180803

Stealing Hidan's heart wouldn't matter because what makes Hidan "immortal" is his Jashin rituals. As long as Hidan keeps doing the rituals, Jashin will keep him alive. If he stops doing them, then he loses the immortality. Kakuzu wouldn't need Hidan's heart for extra immortality, he would just need to practice Jashinism. The only thing taking Hidan's heart would accomplish is give Kakuzu whatever chakra nature Hidan has.