My Prediction of what will occur on Naruto Manga 599 is:
Skips To Sasuke and Orchimaru heading to theLocation of People Who Know Everything At the end of the chapter it will show Sasuke and Orchimaru arriving there and some mysterious shadows or at a angle when we see Sasuke and Orchimaru at the door steps.
Then chapter 600 will have something very big because every 100 chapters Kishi reveals something big.
I explained here: http://www.narutobase.net/forums/showthread.php?t=232068
So at 600 Kishi will reveal the people who know everything and Tobi's face. This is my prediction hope you enjoy. =]