I know someone mentioned this.. but I'll go ahead and post this anyways.
Kishimoto loves using Japanese mythology apparently. Look at the Sage of the 6 path's weapons, they're based on mythology, called the demon brothers or w/e. Izanagi, Susansoo, Amaratasu, Tskuyomi all represent something in Japanese mythology. Amara, being the sun. Tskuyomi the sun. Susansoo was just thing that was snorted out of some random God's nose, which was Izanagi.
All of these were introduced except Izanami.
Now here's my theory on Izanami. Izanagi represents creation and LIFE. In a little brief japanese story, Izanami threatened that she will kill thousand of people everyday. This means Izanami represents death. While Izanagi countered by saying he'll give birth to a thousand people, meaning he represents life.
Izanagi in the naruto world, represents life as well. The Sage of 6 paths, used Izanagi to create stuff out of nothing. He gave life, etc. Izanami is just an opposite. Izanagi represents life, while Izanami represents death.
So I'm predicting that Izanami will be introduced in the Naruto-verse. Maybe it'll be the final EMS technique, or something more then that. All I know that this jutsu will be the opposite of Izanagi.