With Nomura at the helm I highly doubt it will be turn-based. I have no idea if that will be a good or a poor decision on their part, but for my personal tastes: ATB would be nice but I would endorse a different system as well. How many HD ports of FF7 have been released that had the ATB system? Lots. This time they are actually remaking the game, and that goes beyond a graphical overhaul IMO. I'm prepared to see a lot of differences, and I'll be glad to see them. No playthrough of any classic game is ever as good as the first one so I don't think anyone here should be so confident in recapturing all of the magic they felt before anyway. No matter what, a lot of people will be gently let down. And that is ok.
I embrace this remake with arms open wide, and I will take whatever SE throws at me.