Honestly, I just hope they learned from FFXV's mistakes.
The combat system was mostly fine for straight combat, but for people who liked using spells, summons, and other special attacks the series is known for, your choices were horribly limited and the battle system geared for action over classic RPG combat, and to be honest, turn-based and/or ATB was less hassle to choose that sort of thing. Even FF12 did it better in giving you options without stripping out anything cool.
I understand they are giving us old-timers who liked ATB/turn-based something back, I just hope it's good enough for nostalgia while still preserving the good things FFXV did, like battle dialogue to spice things up.
If they go with the overworld like FFXV did it, I hope they make it less boring than how long stretches of FFXV's world could be downright dull. Vehicles in the style of FF8 would be nice until you get other transportation too.