I can't even believe that people think that Kakashi could possibly wield the Rinnegan. Firstly, he is neither a decedent of the Senju or Uchiha clans, this includes Uzumaki's as they are relatives. Secondly, he struggles to handle the basic sharingan, hence why he covers his eye with a mask, not to mention when he uses mangekyo, he potentially runs the risk of killing himself if he is not carefully. Kakashi obtaining the Rinnegan is just plain dumb, and I don't think Kishi is that stupid to fall that low.