Shocking ending, huh...
The death of a main character seems unlikely, but I reeeeeeeeeallly want it to happen. Especially since he or she would probably be guaranteed to return at some point.
Alternate shocker ending: Riku passes his Mark of Mastery, but Sora does not.
Alternate shocker ending 2: Sora is housing some sort of supreme darkness, or the key to Xehanort's immortality, or something along those lines of "good character being the cause for bad thing"
Alternate shocker ending 3: Xehanort is Sora's father
Alternate shocker ending 4: Kairi is revealed to be Xehanort and kills Tidus, Wakka, and Selphie
kupo! I'm excited