I feel like Jinbe isn't a case of if more-so than when. We already know he's going to be a Strawhat in some capacity (being part of the Fleet DOES count imo).
I do think he'll be a fulltime member, mainly cause I have a feeling if we're going to get a tragic backstory for Jinbe it'll be in Wano. Ever notice Jinbe likes to wear Japanese style clothes all the time? I think he has ties there, perhaps raised there as a child. Oh and the 10 shirt in the cover story was not a coincidence I feel.
I think it'll be Jinbe with the crew, and Hatchi being captain of another Fishman Pirate group with Camie in the Fleet.