I think that the letter Sora chases after Pluto with is also the one that he gets at the end of KH2, and for this reason I doubt the letter has anything to do with KH3, because then (if my theory is correct) Mickey would have written it before the events of KH2. Also, the letter was never recieved by Sora in the first place so this could well be true.
If I'm wrong could someone correct me so I can remove this theory from my mind.
If I'm wrong could someone correct me so I can remove this theory from my mind.