Something got me thinking with Vegapunk regarding those Ohara studied as theories..
Rayleigh saying that the straw hats might reach a different conclusion to them at the end of their journey
The whole idea behind the 20 nations forming an alliance under thr oath of an "empty throne" and that there can not be a "king of the world" while that's a big fat lie
Ancient Kingdom being that advanced yet somehow lost to them. With the implications that they created the Df's, Ancient Weapons, allied like lunarians, giants, wano country.
Could go different ways. Maybe the 20 kingdoms alliance had to be formed because the ancient kingdom was taken by Teach's ancestor and using power in the wrong way.
Maybe Joyboy even created the alliance at that time and beat Teach's ancestor but then Imu came into picture and seized the opportunity via manipulation, stole Uranus, gained immortality from the ope ope no mi, became king of the world till he created a new order during void century, played dead and eventually erased all proof of his existence. False hero/peace similarly to what happened in Dressrosa but greater extend.