it was a nice theory, but you have no motive...did kakashi just see the dead bodies and go o0o0o0o0o a sharingan i so00o0o want that for christmass...But besides that your theory is not possible. The time difference is the problem...i am guessing kakashiis in his lat thirties. he was an anbu before sasuke was born and before itachi massacured his family. There is no telling how much time has really passed when kakashi was an anubu...but when he stated in the anime that he was getting old and if he was younger he would of killed zazuba by now, i seriously doubt he ment if he was 4-6 years younger. So i believe it has to do with this obito person, and i am sure the reason will come out eventually.