Heeeeeeeeeeeeeey. Okay so I was thinking about characters from Esat Blue or who appeared in the grand line at some points reappearing. So im gonna make a list of who we might see and what will happen.
I think Morgan will reappear as a first mate pirate of an unexpected pirate crew. Maybe a supernova's. Like Bege or something. I think he'll also have a bit of haki and so will his captain.
Enel maybe too as some evil guy taking over a village or something. I think he'll have some new abilitites up his sleeve too.
And Perona again too and Ussop will think of her as an enemy when she is really Zoro's ally.
And as someone suggested Don Krieg would be good too with more new gadgets.
And Gin too but extremely more powerful and maybe even as a seperate captain.