I don’t see too many happy endings going on at all in FTL. I would lean toward guessing that all of the characters would want to stay in SB. In FTL the characters really didn’t seem to get to think for themselves – everything was dictated by royalty and tradition, so the commonors were subject to having their children stolen and forced to fight in Ogre wars while the Royal lineage was forced into arranged marriages or threatened with death. That seems to be the reason that all the mess with the magic and deal-making happened in the first place – everyone was trying to find ways around the Royal traditions and dictates, or were trying to find ways to climb the social ladder and become a Royal (or get their children to become a Royal).
At least in SB (at least one would assume once the curse is broken) in the real world, people are free to decide for themselves what they want to do with their life. If Astrid doesn’t want to be a nun she and Leroy can be together – there aren’t necessarily any more silly rules about Fairies and Dwarves don’t have any Diamond Mines. Even though MM is a Princess (or a Queen I guess??) she can still be a teacher if she likes it.
That’s one reason I have always thought that Regina has felt that Belle would be a threat. Even in FTL, Belle was a princess who had no problem sacrificing her station in life as a princess to become a maid. She said that “no one decides my fate but me.” She didn’t care that Rumple was a green scaley guy with a bad reputation – she chose to form her own opinion based on what she herself observed and didn’t care what anyone else thought. She is a girl who I think would have no problem at all adjusting to life in SB and would be the first person pointing out to everyone that life is what you make of it. Based upon things that Regina said in FTL, her entire life post killing the King was based upon trying to retain as much power as possible – it was all about having everyone bow down to her. That doesn’t work out so well if everyone chooses to stay in SB, because even the Mayor doesn’t hold “power” in the way that the Royals did in FTL. And without the curse, Regina as Mayor, holds very little power at all.