I think these might be surprises:
kairi dies
sora joins the dark side
sora loses the mark of mastery and goes out to prove he is worth it and kills Xeanort himself
visa-versa
someone important dies
Sora isn't going to kill Xehanort in 3D for several reasons:
a. Xehanort is much stronger than Sora, especially if Sora doesn't become a fully realized Keyblade Master.
b. Nomura said that the final battle Between Xehanort and others will be in KH3.
I also doubt that Sora would join the dark side. Sora understands the balance between light and dark, and how precious it is.
No one said that Sora would lose his MoM exam. I doubt that would happen as well because Sora is a very powerful keyblade weilder, and i don't think Nomura would flip Sora's perspective of darkness upside down.