So lets reevaluate Oda's Jump Festa statement. He said he will introduce a Legend Lurking in the World, which will be the greatest enemy for the Straw Hats, and it will perhaps be related to Whitebeard.
This legend might no have a direct link to Whitebeard, but what if, it has a link to his devil fruit? Like the original Gura Gura no Mi user used it to bury this thing deep within the sea? And the DF the Gorosei are talking about, is actually the Gura Gura no Mi? This thing is touted as possessing the power to destroy the World. So what if, the Gura Gura no Mi, actually has another name? A "Vibration" fruit is kind of a lackluster name for something that should be so powerful.