For the record, I never played the original version of Final Fantasy VII, but I did watch Final Fantasy VII Advent Children.
Then why are you posting in here? And wtf is with everyone watching Advent Children first? Seriously, you don't start out on sequels.
I do not think the plot will be changed if Final Fantasy VII is remade.
And how would you know if you haven't even played VII? They already introduced things in Before Crisis and Crisis Core that will require them to change VII if they want things to stay consistent.
Crisis Core: Final Fantasy VII hints the possibility of a Final Fantasy VII remake. The remake may have an orchestrated soundtrack with some Black Mages arrangements. The orchestra conductor would be Kazuhiko Toyama, who conducted for Crisis Core: Final Fantasy VII. The orchestral arrangements would be recorded by the same studio that recorded for Crisis Core: Final Fantasy VII.
But you're not Square Enix now, are you?