I believe Aeris was intended to die at a later time (after the change from the original script, of course), mainly from the fact of her dialog after her death and evidence I've found on several websites. One is the fact that in the Debug Room, you can acess a secret cave that plays Aeris's theme in the back ground. However, ultimately, Aeris was meant to die, never to return, as Squall of SeeD has already proven. I believe the story was better for it, too. Its not just because I dislike Aeris. In fact, I recently began playing again, and have grown more attached to her. Currently, I'm stand in front of the Temple of the Ancients, but a small part of me doesn't want to keep going, but I know I'll lose her. But thats what the developers wanted. They wanted you to feel the pain of her lose, to mourn her, and to hate Sephiroth for it. And, after seeing all the people who wish to bring her back, it is obvious they suceeded.