Not only Emma, I don’t think Snow and Charming would want to part with their daughter either. I do feel they’ll have another kid someday (if ever David gets a grip on himself lol).
Anyway, I can see them living all (incl. Henry) either in FTL or “our world”. I do feel like it would be better for Red/Ruby to live in SB (or anywhere else on the planet) than in FTL. At least as long as she turns into a wolf. A happy ending for her seems much more likely here.
Gold/Rumpel, well, gods know what would be best for him. If ever he survived that point. Same goes for Regina. Although, moving to a big city and going into politics would be far better than going back to FTL for her. But again, if ever she survives.
Cinderella&Thomas I can see going back. They already are happy, but their financial situation would be much better in FTL. 😉