Oh I am completely certain that she will be present in Elbaf arc, she has so many connections and unresolved issues with the island and its giant inhabitants, however I am far from sure that she'll be the villain here since she has been a major antagonist for so long, and that Oda has screwed-up hard in his writing and treatment of her for so long.
And I suspect that her memory loss and revert as the nice and generous girl she once was as O-Lin is a foreshadow for a more permanent mind revert somewhere later in Wano arc, and doubtlessly through another one of Oda's countless ridiculous plot twists with her.