Board Thread:Theories and Speculation/@comment-28939725-20170414154636/@comment-25122992-20170414163356

Actually, it does. The databook description mentions that user's death is inevitable, and even Obito himself said it to Madara when they and Ten-Tails fought against Shinobi Alliance. Obito didn't die immediately because of the particular reason that was mentioned as well - Black Zetsu prolonged his live as long as he clinged to his body back then. When BZ left his body, Naruto used his Yang powers to prolong Obito's life for a bit as well, but both of them also perfectly realived that Obito cannot be saved and would die later anyway.