Food for thought: Jinbe can't stay on FI? That seems pretty opinionated if you ask me.
Of course you can say that's because of his warlord revokal, but riddle me this; if Fishman Island is not under marine occupancy or surveliance, what's really stopping him?
He seemed to manage fine during those two years we skipped over. Not to say that he's been hiding in the island the whole time; the point is I think it's pretty well established that a fucking ex-warlord can go where he wants without too much worry.
The world government doesn't occupy Fishman Island; it's protected by Big Mama or Tyler Perry or Whitebeard or whoever. Which means that the world government might not even catch wind of Luffy wrecking FI, or even press charges when you think of it; the government and the slave trade are closely linked, if the island is gone then it's pretty much open season on fishmen slaves and mermaids. Luffy destroying Fishman island is actually somewhat BENEFICIAL to the government, in it's own messed up way.
Now, since everything is open to debate, I think it's fair to look at the other side of things too. If the royal family's ideal of peace among sea-people and people actually transpires soon, it could possibly mean allied forces and protectiong for Fishman Island, which means they could drop Big Mam. Now here's the clincher, I think something with Big Mam will go down if this peace between the people comes to pass, which would mean that Fishman Island is the seguing arc into a bigger one allowing us to see REASONS for Jinbe to join.
If this arc just resolves quickly however, I just don't see Jinbe joining. In a larger story arc where he's still an active player? Very likely. But not now.