1: Tobi is Madara, but Madara is already there right? Don't you know how Madara already knew he was being reborn? Maybe, JUST MAYBE -- Tobi is Madara's clone, made from Zestu. Y'know..Just one of my idea's.
2: Remember when Kabuto shown Tobi the "secert coffin" What could make Tobi -- Being such a BADASS be afriad? Tobi could be Madara's brother..Now you may be thinking, MADARA TOOK HIS BROTHERS EYES. Tobi could have taken eyes from another Uchiha member, such as young Tobi, you know where Kakashi got his Sharingan from rightttt? His younger friend, Tobi -- Even tho his other eye was crushed there was still a possibility that his eye was restored.