Contained somewhere within Pangaea Castle is a National Treasure that Donquixote Doflamingo claimed could shake the world. He stated that with immortality, he could have used the treasure to rule over the entire world. So far, its existence has remained a well-kept secret.
The events of the recent Reverie help this theory even more. Not only did 2 members of the Straw Hat Grand Fleet attended the Reverie but also Sabo and the Revolutionary Army were there. I believe Sabo was captured and is still at Mary Geoise.
And a wildcard who we last saw at Mary Geoise is Jewelry Bonney who also has a grudge against the Celestial Dragons. I highly doubt Monkey D. Dragon doesn’t try to rescue his NO.2. I hope you guys see where I’m going with this. Most likely Dragon and Luffy will meet for the first time at Mary Geoise, with them sharing two common goals 1) Freeing Sabo and 2) freeing the slaves.
One Piece is the king of flashbacks and this arc has the potential to have all sorts of valuable and emotional such as Bartholomew Kuma and Jewelry Bonney, why Dragon abandoned Luffy, the possible reveal of Luffy’s biological mother and her past.
*Theory by Specialist_Ad_3192