ok why do so many people keep talking about madara's "real body??"
his body is just old and wizened from being about 100 years old and being severely weakened from his battle with hashirama senju. he now has the uchiha clans dna, the senju clans dna, and the rinnegan. he just needs three more "paths" to make his body complete. maybe he'll use the rinnegan to regenerate his body to make himself young again. either way, he is trying to become the next sage of six paths.