Board Thread:Naruto Discussions/@comment-4682609-20140806081616/@comment-26302001-20140806112845

Well put it this way, Obito's Chakra which awakened Sharingan and Mangekyo and was most likely fused with Hashirama's since he had it so long(which is why he can use perfect susanoo), is now part of Kakashi. It helped him awaken his own Sharingan, which is also Obito's Sharingan. It is most likely Obito meant that Kakashi will eventually go blind, or simply lose the sharingans once they go blind, and revert back to his old eyes.