Quote Originally Posted by Big D
Ya know, it's entirely possible that Materia no longer works at all.
At the end of VII, (SPOILER)a heck of a lot of Lifestream got used up...
It's possible there's not enough energy left to allow Materia to work. But we'll have to wait and see what AC says on that matter...
As Bugenhagen shows in the original game, a planet without lifestream would die. I'm assuming that the entire game isn't based on a world that doesn't exist anymore, so I'm assuming that the lifestream will still exist. While the lifestream exists, mako energy will exist. While mako energy exists, materia will exist, whether it comes about artificially or naturally.