I mean, the simple fact that the combat is action-based means, all by itself, that the Materia system will fundamentally be, from the ground floor on up, different from what we knew in the original. I mean, yes, the "ATB" in VII meant if you dawdled on a decision long enough, an enemy got a chance for a free whack at ya, but it was essentially just a more tense version of good ol' turn-based combat. If a turn-based system makes physical 'attacks' feel more like strategic movement of a gameboard piece--less visceral, more like what using magic 'should' feel like--then an action-based system causes casting 'magic' to feel more visceral, immediate and direct, more like what an attack 'should' feel like..and, unavoidably, somewhat less strategic. Something styled like a 'special move' in the heat of combat is always going to feel more visceral and less strategic than something selected, with patience, analysis of the situation on the battlefield, and a degree of forethought, from a compendium of some kind. That's why RTS games aren't presented like first-person shooters, lol. Seems to me that both options inherently frame one or the other (magic or physical attacks) just as they should be, while unavoidably resulting in the other kind of blending in, and being presented like the first whether it's ideal or not.
Anyway, of course we're going to see a Materia system. They're not totally cuckoo for cocoa puffs. Will it have the same level of depth? Of course not. How they find a way to balance that, though, to at least create the feeling of materia-based customization during the main game, is going to be the central make-or-break element for this RM, in my opinion. Far more than plot elements they might change, whether it turns out Genesis' penis was puppeteering both Jenova and Sephiroth the entire time, Rufus Shinra is really Mukki, etc etc. They fuck up materia, and the game will become a beloved YT video series by whoever does the best job editing the story sequences together in their "Let's Play", and nothing more.