Hey, it's me.
Yeah, I know it'll sound kind of stupid but hear me out anyways...
Tobi might still be Madara..... I have no concrete evidence but just a theory.
Well, I think that everyone knows the ability known as Izanagi which Madara claimed he had. But lets do a brief recap anyways...
"Izanagi is a genjutsu that is cast on the user instead of others and is the most powerful amongst this type of genjutsu. When activated, the caster removes the boundaries between reality and illusion within their personal space. To a degree this allows the user to control their own state of existence. It is normally only active for the briefest of moments."
Source: Narutopedia/Naruto.wikia
Basically, with a skilled enough user this is DA BOMB.
Well, since it allows the user to control their own state of existence, couldn't Madara have simply changed his body? Or maybe even create his own double like Muu did....? It is even mentioned that Madara is terribly weakened, so it's possible that Madara maybe even split his soul.... (I have no idea, I'm just rambling, please continue)
So, yeah that's it actually. I know it isn't as good as many of the theories out there but I didn't put much thought into it, it just occurred to me.
FLAME SHIELD ACTIVATED!!!!
Edit: He even has the 1st Hokages DNA
Double Edit: The new one knows about Nagato