well couldn't it be possible that madara stayed injured after his fight with the first and when kakashi and consorts left obito, he took over his body, still badly injured he did some healing jutsu and voila a whole new body to last him 4 many years to come

, i mean we all see that tobi is nothing like madara, so how would you explain the different posture? and when we saw half his face it looked more like obito then madara ..
I agree. You see, it has never crossed my mind that Obito was Obito. I always thought Madara took over Obito's body to go on living. I was actually surprised that some people it the forum think he is the actual Obito. I also used to think Madara wants Sasuke in order to be able to get over Sasuke's body in case it's necessary, and use him as an ally meanwhile. Please correct me if I'm wrong, my theory may be really strange.