Sorry if this question has been asked before, but does anyone think Arlong and/or Gin will make a reappearance at some point?
I'm wondering about this because it seems like there's been connections between crew members and past events since the time skip. The first one was Nami, where she met Jimbei and learned why Arlong was let out. Originally Jimbei was made out to be a bad person due to letting Arlong out, then we found out that he's a good guy, and made some bad mistakes that led to people suffering.
In some way, you could connect Chopper in Punk Hazard to when we first met him, and also him in Fishmen Island to the initial meeting. In one way, we've seen growth from him, where he has taken control of his monster point. At first, he didn't want to consider himself being a monster, but that has changed. In Fishman Island, he told Zoro that he's no longer scared, and can be a monster if it means helping his friends. In Punk Hazard, we got a look into Chopper still being far from a great doctor. He wanted to help the kids, and while helping them get out, it was Law that saved them in the end. While not making the mistake he did with Hirulik, he's far from his goal.
Ussop had to face his struggle to not allow fear to cripple him in Dressrosa. After seeing the situation he was in, he went back to his bad habit of running away at the hint of danger. He also had to face again what his lies had done, creating a situation which causes harm. Instead of not being able to warn people, he lied to have people fight for him under the guise of a hero. Figuring he could count on just them, he was in the mind set that he had no chance. He finally admitted that fault, and wants to strive to do better. This led to the later sniper scene.
With that in mind, I feel that Arlong and/or Gin could make a comeback for a similar situation. Gin battled Sanji, and he actually would've won if he was truly a monster. The problem with Gin is I don't know how that could correlate with Sanji and facing a past problem with him. He originally didn't want to leave because of Zeff, and that's not a problem. The only thing we have from Sanji is his refusal to hurt women. This is something I don't see changing, as it's been used for gags and if he refused to fight Kalifa, I don't see a situation where that's going to change. Also, we don't know if Gin is still alive.
I can see Arlong possibly returning. Now we could consider the flashback in Fishman Island him returning, but I'm thinking more present time. While Nami has forgiven for what happened, there is still Jimbei to consider. He was confronted by Nami, and was shocked to find out about what he caused. While nothing major was shown, Jimbei seemed to still have sentiments about the old Sun Pirates, and in the Flashback the way the parted each other seemed unfinished in some ways. Perhaps there is some way in which Jimbei feels he must confront Arlong, which he feels he must confront the one thing from his past that could be holding him back.
Thinking it over while typing this out, most likely neither of them will reappear, or at most it would be a quick glimpse at the end of the series about what happened with them. Gin has no reason to return, as he has no bearing for anything to happen. Likewise, Arlong has done his part, and the flashback was there to deepen his character.