tobi is madaras brother they both live untile the thrid war izuna got obitos eye and the unlocked the mangekio by killin madara. Madara only let him because he was goin to revie him with nagatos jutus. sorry for all the misspelled words i was in a hurry.
My first guess is that it is Obito, Kakashi explained that when tobi uses Kamui he is actually existing in two planes of existence, so to me that could explain how Obito could have survived and matured in that other dimension. Kamui is called a space time ocular jutsu so the element of time travel isn't so far fetched in my opinion, and also it appears that Tobi has some history with Kakashi.
Think about the third ocular eyes.. Rinnegan, Sharingan, Byakugan.... who's right eye from the Hyuga clan did Ao get his Byakugan from? which happens to be the same right eye where Tobi transplanted Obitos eye..
I know wat you're saying. I figured out your ideas when you kept hinting about the bloodline relative of Uchiha. I knew you were talking about the Hyuuga. You're saying the hyuuga that Ao took the Byakugan from is the one who has Obito's eye, aka, Tobi.
I will say that..he is not from the uchiha bloodline..because he activated the same mangekyo sharingan which kakashi already did ..so he is not obito,not kagami,nor izuna uchiha or any other uchiha clan member...he would be known by madara .because he has never shown jutsu like genjutsu,Amaterasu or sussano..so if at all he is uchiha he used to have one of this jutsu in his eyes ..but he didnt showed it or used it..so i m thinking who this guy might be..i have got no clue..he knows much about leaf village and the bijju's ..so he would from the time of third hokage is bring appointed.
I tend to believe now that Tobi is a combination of Zetsu Madara and Obito. There is simply no way to explain how he has been operating as long as he has given Obito's time of death, unless he was alive before finding Obito. In addition, we simply can't ignore that Zetsu makes up a large portion of Tobi and the fact that he shares eye lines identical to Madara, plus some new ones due to age:
Well, Kakashi has a feeling it's Obito....and y'know, Kishimoto likes to bs us....so I'll say it's Obito. I've always thought Tobi was Obito....so....I'll stick with that answer. One because Kakashi has shown a bit of concern, plus Tobi has the other eye of Obito, and secondly, I don't want to over think or over analyze anything.
this chapter is going back to the madara fight anyway, then to sasuke maybe in the next chapter, then back to the naruto fight. there's still things we need to know as readers before we know who tobi is.