Okay, I'm not arguing that there is a great possibility that madara=madara, but there is still one question that hasn't been answered.
Why does he wear a mask if not to conceal his identity???
If he truly is who he says he is, why has Kishi never outright shown us? There HAS to be a secret behind this madara w/ mask that Kishi isn't ready for us to know. I am not by any means saying that Madara isn't Madara. All I'm saying is that he has a secret behind that mask, and we can't know what it is until we ACTUALLY see it.
bcz is more cool?? look KAKASHI is wearing mask and nobody see kakashi real face.... and mask wearing is a typical "ninja thing"....
in the time being in akatsuki he did it because of acting like tobi so noone would know he is madara.
then his mask got shredered by konan and he made a new one, cause he cant show his face to sasuke ... itachis amaterasu is to dangerous.
and finally hiding his face with a , again diferent mask , as he met itachi and yamato. as he explained it was so no one could find him but even so itachi new about him and set a meting. about wearing a mask in minatos presence ... he is just shy

or maybe he wanted everyone to acknowledge him and not the uchiha clan who attaced konoah or he is using someone elses body wich would explain his hair changes,
madara vs 1st long hair --- madara vs yamato short hair --- madara mets itachi long hair --- and madara now short hair

or his hair is just growing and sometimes he needs to cut it
and he looks pretty mad with a mask especially the new one .. maybe he is trying to show his new powers with new masks.
but still there is not even now a single proof that he is not madara until then .........................................U_U