hmmm, possible, but i dont think he would be that calm all the time if he did ya know?
now i just put this together in my head so bear with me lol
but what if he is a container for one of the tailed beasts?
like he said, his immortality comes from his chakra, what if the beast thats in him is fueling his chakra enough to keep him alive all of these years.
and maybe he discovered a way to have all of the beasts contained in him at once, that would explain why Akatsuki are collecting them, i think Madara is just trying to manipulate them all to his will, and the mask probably covers up the mark the beast left on him (i.e. Narutos whisker marks, Gaaras black eye rings)
oh wow, i just realized that it could also be possible that the mask is to cover up the veins and red face and all that stuff that comes along with opening the gates, and i thought about the fact that he's been alive so long, he has probably gained full control of it, so disregard that comment about him being "too calm for it" lol