Lock leaves for a quest to find the Ultimate Treasure, and Celes and Mog go with him. Since Umaro is friends with Mog, he probably goes too. Setzer likes this particulat kind of gambling and provides his airship, probably helping Lock to get information.
Tina looks after the kids in Moblitz and continues to be their mom, except for Katrina's and Dean's child, for whom she becomes "Aunt Tina". After a while, she discovers more feelings and she could be going to have kids of her own. But I can't think of a suitable father.
Edgar goes back to be King and turns Figaro into the main technological city in the world, and and Mash keeps training with Duncan.
Relms keeps painting for Owzer and eventually he propels her to be the most famous painter in the world. She settles down in town together with Interceptor and Strago, who still always enjoys a good quarrel with Gunho.
Cyan remarries and has other children. He trains them to the art of swordfighting, while keeping on making his fake flowers for his wife.
Gau is probably looked after by Tina or Mash. He could be made to go to school, which could bring to very funny situations.
GoGo joins a circus and amazes the public with his/her Mimic skills.
Shadow... well, he stays dead.