User blog comment:Omega natsu2/Chapter 368: The Third Seal, Predictions./@comment-7418318-20140120165720/@comment-121.74.58.57-20140120232352

Or Naruto gets Sasuke's original eyes (Sasuke now "wears" Itachi's eyes) in some way and gets a rinnegan this way.

But there has been a bit too much eye transplants lately, it has become more common than swapping new underwear (which is something we never see the chars do, so it IS more common :O)