Okay- lemme explain this FOR THE LAST TIME! Kingdom Hearts is not chronologically correct in any way whatsoever. It is not meant to be taken as part of the FF chronology. It was just a means of bringing back old characters and throwing them in an interesting survival situation. Think of it as a parallel universe with the same people- just placed in different worlds. (SPOILER)I mean since when did Squall, Yuffie, and Aeris grow up together in Hollow Bastion, anyway? And when did Tidus, Wakka, and Selphie spend their childhood in Destiny Islands with Sora, Riku, and Kairi? It's an alternate reality. It's a seperate story.

Anyway, back to this thread's topic- most likely, Aeris won't be in FFVII-2. That is unless it's a prequel and then maybe they could show her life before she met Cloud. (SPOILER)Of course, it could be like Tidus's reappearance to Yuna in FFX-2. She could be a spirit who comes back in times when Cloud needs support.