Well i think that tobi is obito, here are many explanations
-left eye is only showing and has sharingan like wise obito
-has the same letters in the name
-half of a medal body and half of obitos body was crushed
-look how kakashi akated when he saw tobi show his sharingan
-tobi acts silly and is always l8 likewise obito
-is uchiha blood
and madara could still be alive i mean it dosent meen hes tobi...