A Final Fantasy VI remake isn’t impossible, but don’t expect it soon.
FFVII Remake director Naoki Hamaguchi says the team is focused on finishing the FFVII Remake trilogy, so there are no plans for an FFVI remake.
Original FFVI co-director Yoshinori Kitase says remaking the game would be a huge challenge because it has a massive cast of playable characters, multiple story paths, and a ton of optional content.
Turning all of that into a modern AAA game would take a lot of time and resources.