I don't think it'll be completed before the New World. A character joining usually requires a full arc. There will be their reunion (really bad timing to add a character) and then FI. So I see them getting a new crewmate at FI, and one spot being left. There's a long way to go to the end, after all.If the crew is presumed to be completed before the New World, one fishman and one among the already introduced characters feels more likely. The fishman, who is not Jinbei, can't really be predicted without baseless speculation yet, so the other one is the baffler.
Unless Oda decides to troll us and put of FI for another hundred chapters.
At least Jinbei and Hancock have a direct connection to Luffy and a motive to go with him.Point being is, that Hancock/Jinbei/Perona are such a bad choice for potential nakama, that Bonney is looking pretty good atm ( even tho I must admit its kinda fked up) only with that kick in the face of BB, and the hint of background related to the WG.