It doesn't prove it but the circumstantial evidence is starting to pile up. I wasn't a believer before since it seemed so far fetched. But now everythings pointing towards it. But for those watching/reading One Piece, when the guy that looked like Sanji's wanted poser showed up it was indicated that it was supposed to be someone with a connection to one of the Strawhats. And everyone was speculating on who it could be. Then it turned out to be a whole new character. This could be something like that. Someone that knew Kakashi from before. Maybe even with a connection to Obito. A big brother, father or just friend or rival. But if it's someone already introduced it lean toward Obito. But since people mentioned Sasuke timetraveling (just for giggles i guess) what if Tobi is Kakashi timetraveling.

Many possibility's, but i personally think it's someone that hasn't been introduced. And if it is someone that we know then i must jump on the Obito bandwagon. But i hope not since this all would spit on all that Obito said and stood for. Even though Obito only got a double episode in the anime he became one of the greatest from Leaf IMO. And Kakashi himself changed himself completely because Obito showed him the way.