Danzo & Madara has been subject of intensity scrutiny for almost a year by hard-core Naruto fans. Now, there's a possibility the debates will intensify! What if Danzo suddenly has Sharingan? Of course, it doesn't necessarily mean he is Madara but one thing's for sure it would fire up the fans - again. One thing about Masashi Kishimoto is he leaves clues that intrigue fans (of both the manga and the anime) and to make them discuss the story.
Here's a counterpoint to the argument above from youtube:
Whoever they are -- my interest level in Naruto is back to sky high again.