I would be pretty upset if they changed Aerith's fate.
Playing the original game back in 1997, it was absolutely shocking for a main character to die in this manner and not allow for them to return to the party later in the game. I mean, how could they kill her? She had a level 4 limit break and everything!
I spent the rest of the game searching every nook and cranny for the method of reviving Aerith, looked in all game guides, discussed it in an IRC chat room, but there's no bringing her back and by the end you have to accept it and move on.
This was a rather powerful message to me at the time, a dumb high school kid who was on the verge of losing a grandfather. I don't want to say that the death of a videogame character affected me more than losing my grandfather, but it absolutely better prepared me for dealing with loss and the permanence of it.
Also, you can't replace Tifa with Aerith and make it work. Cloud didn't go on a date with Tifa at the Gold Saucer after all...