Things I would expect from the game
- Large world
--- Including several modes of travel, but not just skipping zones
- Chocobos (and all their details in terms of breeding, areas you can get to with them, etc).
- Materia system (perhaps even more intricate)
- Long ultimate weapon quest chains
- Turn based (get that active time battle shit the fuck out of my FF games (even though the combat system of FF XV isn't bad))
- Story to remain the same (while updating it with fixing some of the unfinished side quests)
- Ultimate weapons, lots of summons and hidden ones (exploring should be rewarded, and it should not be a story following a linear path).
Random battles or visible, I wouldn't mind if they mixed it. Though since FF 7 was of the open formula. Once you got out of the city, you could explore into places that got you horribly killed as you didn't know you were in a higher level area until a level 50 dark dragon attacked you. I landed on every single little island, and there were quite a few with different mob placements.
Basically I expect "more" of the remake, but certainly not less. Not one core mechanic, side quest, mini mission or area should be gone. I expect to be wowed by a new golden saucer area with lots of things to do, not wondering where it is. I'd easily be satisfied with a revamp graphically. It is the later FF games that need entire "remakes".
FF 7 had so many things going for it, that remaking it into a visually pleasing experience for todays graphic hungry audience will leave them wondering what the hell happened to the series after it.