Madara and the Moon's Eye
This might be farfetched and/or a too long read but bare with me
Tsukuyomi is the god of the moon in Shinto and Japanese mythology.
Izanagi which was summoned by the first gods ended up creating
Amaterasu (incarnation of the sun) from Izanagi's left eye,
Tsukuyomi (incarnation of the moon) from his right eye, and
Susanoo (incarnation of storms and ruler of the sea) from his nose.
Izanagi went on to divide the world between them with Tsukuyomi taking control of the night and moon.
Sasuke used his left eye when he used his Amaterasu ability, opposed to Itachi who used his right for some reason. In this case it looks like Sasuke is the one in line with Shinto. Sasuke used his right eye to supress Amaterasu. (Which makes sense because the reason why night and day never is together is in Shinto, because Amaterasu who represents the sun was furious with Tsukuyomi who represents the night. That is why the right 'eye of the moon' would supress the Amaterasu's fire created by the left 'eye of the sungodess' and vice versa)
With that said lets move on to tobi/madara. In Naruto 386 page 11 | One Manga Itachi says "Today Madara is a pathetic shell of his former self. He is no longer worth being considered the greatest Uchiha."
This leads me to believe that Madara has lost some of his power, a huge key to understanding just what it is he has lost is that he(tobi) ever only shows his right eye. He is evitently covering up a secret about himself. I think he is covering up the fact that he has lost the power of is left eye, perhaps not completely who knows. Since why else would he purposely hide 50% of his EMS? Knowing this I can think of 2 plausible alternatives
1, Either the "Moon's Eye plan" is to cause whatever havoc he can with his right eye (the right eye of the moon) possibly something that could lead to a 4th ninjawar. Possibly some kind of genjutsu on the Kages, as his eye is the one that deals with genjutsu. Something that stengthen this theory is that in Naruto 453 page 18 | One Manga he says "I've had enough of being cautious" which suggests his plans are to take action in some form (what that is will be pretty impossible to determine until we get more clues) Another reason why it's his 'eye of the moon' that is still active is that he was able to put out the trap-amaterasu that Itachi planted on Sasuke. The less convincing alternative is that
2, He, much like Itachi, has reversed eye-order. His right eye is the Amaterasu eye meaning it's his 'eye of the moon' that has lost it's power. Therefor he means to restore it making him essentially immortal again. He could be restoring it by taking Sasuke's eye, afterall he knows Sasuke is planning to attack the Kages which means he would without a doubt have to use his MS.
What do you think of these 2 ideas? can you think of other plausable ideas too? Feel free to discuss
I've been thinking how Madara tends to operate when it's full moon. Helping Itachi with the Uchiha slaugher, the 9 tails attack on Konoha as examples.. I'm yet to figure out a connection with the full moon though.