https://www.dualshockers.com/final-fantasy-vii-remake-materia/amp/
Equipping system will likely remain unchanged, but Materia effects will change to accommodate the different combat system.
What Materia do you see needing a change? For me, E. Skill and Manipulate come to mind right away. I can't see that mechanic working in this combat system.
I can't say that I'm surprised, given the entirely different combat mechanics in the remake. It's only logical that certain materia effects cannot be tranferred 1:1 from the original.
I'd say most Magic materia can stay as they are, perhaps with some slight tweaks (maybe introducing a sort of 'casting time', like FFIV had, for example?).
The basic summon mechanic could be left intact as well, or they could make the summons appear as temporary additional combatants like in FFX or XII. My personal preference would be the classical one-time summons, but who knows what they might come up with.
Materia that definitely won't work in an action combat system are all those that relate to physical attacks, e.g. Double Cut (judging by the trailers, everyone and their mom already seems to have 4xCut or more as an innate ability, lol), Slash-All, Death Blow, Added Cut, Counterattack, Counter, Magic Counter. How will counterattacks be handled in an action-RPG anyway? I imagine the entire mechanic needs to undergo a huge change to still function properly.
Since there is no longer a change from 'field screen' to 'battle screen', Materia like Pre-emptive or Sneak Attack will also be among those that'll likely be either dramatically altered or scrapped altogether.
I can see them keeping All, Elemental and Added Effect, as those only define your targeting and elemental/status properties, so that shouldn't be a problem. All could likely be altered a little to encompass a certain area or 'effective range' for the spell, and that area could get bigger by leveling the materia.
Stat raising materia should be fine as well. I could even imagine them keeping Enemy Lure or Enemy Away, making them work by having the enemies move in on you/away from you as you go around exploring.