We've scoured the internet and here are the best predictions we've seen for season 6 (which premieres this Sunday at 9pm)
Predictions (in no particular order):
1. Melisandre turns Jon Snow into a Potato. She turns him into fries and feeds him to Ramsay Bolton, who then chokes on a fry and dies a horrible, satisfying death. Sansa takes back Winterfell.
2. Ned Stark is alive. Turns out he was chilling in middle earth with aragon and the hobbits this whole time.
3. Hodor learns to say something other than "Hodor"