The most important change that should be made to a hypothetical Final Fantasy VI Remake is for them to turn it from 1 game into at least 2 games. One game for the World of Balance and another for the World of Ruin. This is the most important change that could possibly be made to Final Fantasy VI and I think that it would add a lot to the game to do this. Or, should I say, dividing it into at least 2 different games would allow Square Enix to put more game into Final Fantasy VI. Think of all the World of Ruin fetch quests and minigames they could add. Think of all the additional lore. There would be a lot of things only possible by turning it into multiple games that couldn't be achieved with just 1.