@Wintermute:
Nice idea! This will lead to Bayonetta be the nakama. I approve.
I would love that. Make Jeanne join too. Sanji will die from a nosebleed.
–- Update From New Post Merge ---
@xioaxioa:
I'm probably going to get a lot of flak for my input, of course it deserves all the flak it gets. I don't like the character or what I'm going to say, and I know a lot of other people don't like this character, but a lot of people don't like Jinbie for Zoro, so likability has nothing to do with probability. A Character I see a possibility of joining, but I don't want to join, is Momonosuke. Up until the last few chapters, I figured he had no chance of joining. After hearing about him and his story; it got me thinking. For two main reasons I see it as a possibility. The first is that his father was a "pirate" on Rogers ship, setting out to sea against his retainers wishes. Momonosuke could easily do the same. But what reason would Momonosuke have to set out with Luffy? Well, the only person in the whole world who could give him back his families heritage is in Luffy's crew, Robin. Enough with the (2) pro's, now for the cons. Momonosuke is too young. Luffy's crew contains members who hold the record for the youngest (8) and second youngest (15) bounties. Momonosuke is too weak. Does everyone in the crew have to fight? Nami's only had 2-3 real fights. Momonosuke is too weak to face Black Beards crew. Black Beard has 10 captains and Luffy want's 10 crew members. Does an apprentice count as an official member? ie Zoro is "the First", Brook is "the Eighth", and Momonosuke would be "the Apprentice". Then we would still get the ninth and tenth. Now it's not really a point for either side, but his dream to be the Shogun would be the only other "strength" related dream beside Luffy's and Zoro's, if he were to join the crew.
I should really reiterate: Before I was against Momonosuke joining. Now I'm not for nor against. Everything above was devils advocate and I have no desire to defend nor support it. I fully expect people to tear it apart and the seems, so go at it.
As far as his heritage goes, in other words how to read Poneglyphs, I see it becoming obsolete once Luffy reaches Raftel. Because honestly speaking that's what should happen. The whole point of this manga is for Luffy to become PK and of course showing his journey his nakama etc. But that's the goal that was set from the very first chapter.
So in theory Luffy when he finds Raftel and uncovers the One Piece, whatever it is, he'll also uncover the truth about the Void century thanks to the Rio Poneglyph. Inuarashi's words seem to reflect that, the part about Roger revising his course and studying the Poneglyphs. So what I'm saying once the Rio Poneglyph is complete, and the truth about the secrets of the world is revealed, the Poneglyphs would have served their purpose.
Oda is setting things in a way that the SHs will do what the Roger pirates couldn't do. They weren't able to use that knowledge they got about the Void century, it was too big for them. So I do think there's a rather big chance to see Luffy go against the WG, and start the final war after he learns the truth about the Void century.
So he will make it known to the world, and the revos are sure to help him because they're also interested in the Void century, at least Dragon is. Everyone wants to know the WG's dirty little secrets.
So in conclusion I would say that at this point of the story it is not vital for Momonosuke to endanger himself by sailing with the SHs, just so he can learn how to read Poneglyphs. Furthermore I would say that nothing should prevent Robin from going to Wano, after the end of her journey, and teach Momonosuke how to read them. And honestly it all depends on Momo, if he really wants to learn how to read them.
So for now the only valid reason I see for him to join would be because he wants to become strong, so that he can one day become the Shogun since it's apparently his dream.
But another issue rises is that technically he's the heir of the Kouzuki clan, with Oden and his mom dead there's prolly no one left to take the position of head of the Kouzuki clan. It should be Momonosuke, so as Daimyo of the Kuri province he should have duties to attend to, once all this Kaido business is over.
We don't know how Oden was able to leave his position in Wano and sail all over the world with Roger. Might be that he wasn't Daimyo yet and someone else, his father for example, was at the time.
Because I imagine him leaving would leave a vacuum if he really was the Daimyo at the time.
Well I'm not completely excluding the possibility that he'd join, although I feel he adds very little to the crew. Since Kinemon and him aren't father and son,I'd rather have Kinemon join, since unlike before he won't be leaving his kid behind or something. But if only for becoming stronger maybe Momo should join, but honestly I'm not convinced he's the best candidate.
On the other hand with the Luffy, Nami, Chopper and Brook going to Wholecake island, there's a rather big chance they will run into Jinbei there. He should have also received a summon to the tea party, because that's what it is. So he has a big chance of joining at the end of that arc, after he deals with the business he has with BM, whatever it might be. He can even bring the Poneglyph(s) with him, on Wadatsumi.
Yet another reason for him to join.
And lol sorry for the wall of text.