I disagree that Tobi has got to Obito now.
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shows tobi saying that he doesnt want heroes to make pitiful stories at the grave, and then there is a picture of kakashi at obito's grave. Lets remember that half of obito's body was crushed we did not see anything about his eye being crushed, it just wasnt visible. Tobi cannot be Obito and here is why, why the hell would Obito talk to the 4th hokage as if he didnt know him, i mean he was his master after all... Tobi just stole Obito's eye which connects him to kakashi through obito. The only 2 real possibilities are Kagami uchiha and Izuna uchiha. Kagami would be the perfect age to be A tobi. He is linked to the 2nd hokage who knew space-time nin, and is presumably around the same age as danzo and the others. kagami is assumed to be dead, but if he was teamed up with the 2nd hokage, the elders, danzo, hiruzen, wouldn't we have heard about his death? Someone that powerful doesnt disappear so easily.
As Itachi was a double agent for konoha, it is my belief that Kagami was a double agent for Madara. he got close and befriended the tobirama group, but he as never on their side. Using his sharingan he was able to take what the 2nd hokage used and perfect it. Since the databook says that any sharingan can master kamui, it was not difficult for a sharingan user to mix the two into a complete technique.
Kagami fits tobi perfectly, the age, the techniques, his knowledgem everything.