During the fight between itachi and sasuke, itachi said that madara was an invincible immortal and that the only one who could surpass him was himself. http://www.onemanga.com/Naruto/386/11/ So we can say that at that point, madara was till stronger than itachi since itachi hoped to surpass him. then itachi talks about claiming a power greater than madara. remember that cause that's immportant. Then itachi tells sasuke that sasuke will be his light. http://www.onemanga.com/Naruto/386/12/ As we know itachi plans out every detail and usually has a purpose behind everything he says and does. That's why I dont think amaterasu was the only power implanted into to sasuke, and i think his new sharigan has powers that even surpasses madara right now. When itachi said he will gain powers that would surpass madara and sasuke would be his new light, he was speaking of giving sasuke powers thus living through him. He also made a point earlier about how sacrifices played a big role in the uchia clan. But itachi's sacrifice was different therefor i think that theirs two choices
A. http://www.onemanga.com/Naruto/386/09/Some how he was able to transfer a very part of his soul into sasuke. That would solve the problem of blindness since he would be changing host.
B. His willing sacrifice probably open a whole new sharigan above even the ms. that would explain the "power" he was refering to that would surpass madara.
either way sasuke would beat madara if it ever came down to it. the power that itachi was speaking of is now within sasuke. and itachi's role is not over in the story line.