I know this is an unpopular opinion but I want them to change the gameplay to a more modern action-based system like FFXV. As much as I love the PS1 era FF's I don't look back at them fondly because of the gameplay, the materia system/junction systems or anything like that.
My love for the series comes from the characters, story, worlds etc.... they could make it a First Person Shooter for all I care as long as the rest is intact.