Totally crack pot theory with no basis BUT I think that maybe, being that right now the oldest people with some magical world affliations, the organization running Tamara and Greg is actually run by the Darlings. There’s a connection between all these worlds obviously, and Mr. Darling himself had a connection to NL, so why not a connection between Bae and this organization. Maybe they’ve been looking for him for a long time?
Second whacked out theory – the beans don’t open portals but Wormholes to other worlds. Worlds where science and magic are a medley and time passes differently based on the planet’s distance from the sun. So Storybrooke is like a permanently opened wormhole that is about to shutdown. Thus there are infinite worlds to travel to, not dimensions. This opens up the possibility of other franchises that Disney owns, which I believe Star Wars is now one of.Though I doubt that would happen soon.