I still find Jinbe's backstory and dream (the one that doesn't exist) too lacking. On the other hand, he was there two years ago, he wants to join, and in terms of dream, Brook's barely any better -.-
So … the Kinemon argument. He uses two swords, which sandwiches in nicely between Zoro's three and Brook's one (although it looks like Kinemon often uses just one sword, similar to how Zoro often uses less than three). Moreover, Kinemon fights with fire in his Foxfire style, similar to how Brook added an ice element to his fencing style over the timeskip. So, in terms of fighting abilities he seems to fit very neatly into the crew. Moreover, he's amusing (his face, for a start . . .) in that he is an honourable samurai who never complains etc. but you can tell he's contradictory to that (e.g. hilarity with Nami, and talking about running in teh most recent chapter).
He's a dutiful man with a kid, plus, he 'hates pirates', so people think he won't join, however: by the end of the arc, he'll be getting along with the Strawhats anyway (see Nami in teh Buggy arc) so the first isn't so important. The second ... well, it is quite possible that he will leave his son with appropriate family back home and also possible that Momonosuke will die at PH (although, it's Oda, so that seems unlikely).
Anyway, it seems quite likely, considering teh arc as it is now, that Kinemon and Momonosuke will travel with the SHs to Wano (either directly or with some stops on the way . . .) after PH (there aren't many ships, right?) and, as well as with the events of this arc itself, Kinemon might become more like an 'outsider', integrating with the SHs, similar to Vivi, a little. This could lead to him being seen as an outcast/traitor or something at Wano, which in turn could lead to, by the end of that arc, him joining the SHs (and not marking his son with his ... uh ... shamefulness).