Probably Rumple and Regina will “succeed” in getting what they thought they wanted only to discover it wasn’t what they’d wanted after all.
Speaking of Rumple, where’s he at in this AU? Did he let Belle’s kiss break the Dark One Curse? Is he even in FTL, or has he found a way to our word and is enjoying a life with Bae? Did he never become the Dark One at all, and he and Bae lived full lives and died centuries ago? If so, who’s the Dark One instead of him?