I can, for the most part.
For the battle system, retain the original Active Time Battle, but:
1) Increase the pacing of the battle. Take inspiration from Bravely Default by allowing us to speed up battle animations and such, let us skip summon animations, etc.
2) Either random encounter AND the encounter slider from Bravely Default, or visible enemies on the field with seamless encounters, like Chrono Trigger/FFXII. The former has the advantage of keeping true to the original level design of map areas, potentially making them feeling more tight and detailed looking as they don't have to accommodate the enemies. The latter means larger area and seamless encounter, but it'd be weird to see map infested with creatures and such, and the maps might be less detailed-oriented.
3) Needs a lot of balancing work. Omnislash/Mime/KOTR/Final attack+Phoenix/Double summon, all needs tweaking for the end game. At the same time, make the game more challenging, perhaps difficulty options.
4) Add more materia/weapons/armors/accesories choices. Give them interesting effects that can provide various customization possibilities and options in battles.
5) Story/character wise, new and improved translation to the same original script, no if's or buts. Voice acting optional. Remastered soundtrack by Nobuo Uematsu, again optional. Cutscene skip, same thing.
6) Keep the silly/lighthearted stuff. I have no idea how they're going to make Cloud dress like a lady, but do it. Just do it. I don't even care if I'd cringe hard, but it'd be glorious.
7) World map/airship is the hardest bit. I doubt they'll make fully traversable field map like FFXV, that'd be insane.