I like this theory. Because it could mean one thing.
Up till now it appeared to me that the manga will end after Oro and Akatsuki are defeated.
Because it would be very time consuming and cliche (Dbz wore it out, although i loved ssj 2&3) to introduce another villain which is stronger than those before him.
But not if he was already introduced.
Madara/Itachi could rise up to it and may be using Akatsuki all this time. Who knows.
I'd like that theory to be true, because it'll mean the manga has to go on for a longer time. Without becoming a dbz clone in terms of bad guys (don't get me wrong I love db)
"For Feanor was made the mightiest in all parts of body and mind, in valour, in endurance, in beauty, in understanding, in skill, in strength and subtlety alike, of all the Children of Illuvatar, and a bright flame was in him"