User blog comment:Kaido King of the Beasts/The Fourth Road Poneglyph/@comment-1712781-20160321202655

Doflamingo said the ability to switch bodies with the fruit would be invaluable in relation to the treasure..

my train of thought was they have an immortal D hostage or something like that, or at least a survivor of the void century, the previous recipient of the immortality surgery..but i doubt he'd want to switch himself, so maybe popping in one of is own people like Vergo to replace them was the plan? but it would give him the power to take over the world ,so i figured it would be more like the original world governments king or something that they all answer to, like Gwyn from Dark Souls.. who knows. nothing to really base any of our guesses on. theres still the theories about Bonney influencing the age of the Gourousei.

I'd love for it to be the last Road Poneglyph but like you said having only one doesn't really help, your original guess that its Uranus kind of makes more sense to shake up the world and we STILL don't know shit about it.