The return of Joy Boy
To figure out who Joy Boy is ne might ask if there are still descandants from the Ancient Kingdom, I would say yes. The 20 nations (except Nefertari family/Alabasta) decided to live on top of the Redline and become a group named Celestial Dragons. These Celestial Dragons are the privileged minority ruling over the World acting like being Gods. In Laws flashback we learned that the father of Doflamingo and Corazon was a Celestial Dragon who decided to become a normal human.
In one point of the backflash Law asked Corazon whats the meaning of the D., followed by Corazon telling him that the D. stands for “Gods natural enemy”.
Especially with Corazon saying Celestial Dragons can be seen as these gods one can conclude that the D.’s are the descandents of civilisation. This results in the assumption that the new Joy Boy should be part this “D. Clan”. And who would fit better than the main protagonist of One Piece ? Who is actually called Monkey D. Luffy and thus part of this “D. Clan”. Are there more hints, of course there are! I expect many would go the and compare Luffy with Roger, but since we learned through the story of Oden that Roger never was a “Joy Boy” I will try a different approach (long time many expect sth. like Joy Boy -> … -> Roger -> Luffy). At Twin Cape the Strawhat Pirates met Crocus who was the doctor of the Jolly Roger Pirates. After Strawhats left Twin Cape we saw Crocus talking to himself.
The ones we were waiting for, for me definetly a reference to the outcome of Jolly Roger Laugh Tale adventure. Also interisting in Odens flashblack we saw the Sea Kings saying that ones the Kings returns the whales will be happy again.
Now look back what we see the moment Strawhat Pirates entered the New World for the first time!
I think there was actually noone doubting anymore that Luffy is or will become the new Joy Boy, but I hope these points just strengthen this idea. Lets head to the next one!