Well I don't know if its really answered but, to me in my opinion Xion will return in kh3. I know some say that she can't return due to the fact, everyone forgot about her, it will mess up sora's memories, she was only there to fit in a plot hole etc etc. But for me i think she will return from the "key to return hearts", maybe she had a replica heart or something? Like she said before, even if she will be forgotten the memories of what she did will always be there. Maybe the reports of the organization are still there, sure they said the memories of her are forgotten on their minds, but what about the reports? Sorry for not really able to explain to much about it been a while since I wrote a theory . What do you guys think?