I actually don't think Tobi is Obito, and this is literally a massive troll on Kishi's part. Obito doesn't make any sense if you think about it.
A. Kisame RECOGNIZED Tobi and made it very clear he was a prominent or famous ninja who Kisame could trust. Seeing as, if this was Obito, he'd have to work in the shadows to protect his identity after surviving his "death," Kisame would not be able to recognize him.
B. Tobi claimed to have given Nagato his Rinnegan. Nagato was born waaay before Obito. In fact, Minato was a child at the time.
C. Tobi's limbs seem to grow back very similarly to Zetsu's. He has a definitive connection to Zetsu, and