I have suspected for awhile that Madara's eye of the Moon plan is only step 1 in his goals.
Step 2 would be using a justu to recreate the world and I have suspected this may be Izanami. Once everyone is under his genjutsu control he can manipulate their chakra and he will kill everyone then use their chakra energies to reform the world in his own image using Izanagi.
Death and Rebirth the final end goal of Uchiha Madara!!!
That actually sounds like a nice plan.. Use Izanami+Izanagi together.