I feel like the discussion is getting off topic based on the original post...
Anyway, related to the original: (Going to use 43051's way here)
Quote, Curly and Balrog end up finding a perfect place to stay and live out their carefree days. It could be speculated that the three end up finding Sue and them and staying with them, but it's all up for the viewer to decide.
The Sakamoto's and Itoh reunite and return to the surface with Santa and Chako. Once again, it could be speculated that they stay on the island to do the research, but it's up for interpretation. Sue and Itoh probably aren't reverted to human form just yet, but they are working on a way to fix it.
Misery and Jenka are no longer fighting each other and practice with each other. I've got nothing to add here except that Misery is thanking Quote secretly for ending the curse on her and Balrog.
Jack (Yes, don't forget about the mimigas now!) escapes from the doctor and is the new leader of Mimiga Village/town and is doing okay along with the others that ended up turning against The Doctor. (The few who didn't believe the doctor, such as the ones in Jail #2 and some others)
That's done with, but getting back to the island theory...
It could be that the Island floats by itself, but with Ballos, the negative energy that he releases when angered (The one that destroyed the kingdom he loved) is enough to bring the island down. The core was created possibly by Jenka (Or was already on the island as the keeper of the entire island) in order to combat this, so the Island wouldn't fall. But if both are destroyed, it removes the added weight to the puzzle.
Island = float
Island + Ballos = fall
Island + Ballos + Core = float
Island + Core= float