I wonder what could add Momonosuke to the Strawhats crew?
No experience, no strentgh, lack of decision and strong will, lack of usuful abbilities for support and contribute, lack of a dream of his own far away from Oden's will.
The only thing i see from Momo's part is tits comedy with Nami & Robbin
This will be a long post, so you'll have to bear with me. xD
Tbh, I actually can really see Momonosuke being part of the Straw Hat Crew. I mean, let's face it... after Wano gets cleansed from Orochi, Kaido and the Big Mom pirates, Momonosuke is not ready to become Shogun.. he's only 8 years old, and doesn't have the experience nor the knowledge required to become Shogun.
This is why I believe Momonosuke will emulate his father and leave Wano, becoming one of the SH Pirates...a way to explore and experience the world as it is, and also to answer the question and significance as to why Oden risked so much to open Wano's borders.. maybe even witness the importance of the poneglyphs, and why it had been passed every generation in the Kozuki clan the ability to read this ancient language... maybe also to know what role his ancestors played, in regards to the poneglyphs and the world, which could connect to momo's role as Shogun.
As Oden is now dead, these questions can no longer be answered, and back then, Momo was an immature lad who felt entitled.. But I could see his character develop in Wano to question things like this.. I mean, yeah.. he's 8 years old, but soon, he'll know the responsibility he shoulders.. His role in Udon prison was the stepping stone of his character development.. and as Wano advances, he'll develop more and more.
I'm willing to bet that he will not even consider himself worthy of Shogun by Wano's end, due to knowing his responsibilities as his develops more in this arc - in other words, he's not ready yet... But his journey with the SH crew would allow him to find answers to all this.. as well as his family's role, and give him the knowledge and experience needed to become Shogun and lead Wano.
As for his role?
An apprentice... I mean, with OP nearing its end, it would fit to have an apprentice in the crew, like Shanks, Marco or Kaido were, no?? But in this case, an apprentice, whose existence plays a big role in Wano, and maybe even the politics of the world in the future, since Wano would open its borders again, and Luffy catalyzing big changes in the world.. This also connects Jinbe's ambition of making fishmen accepted as well.
And his dream is simple... To become Shogun of Wano, but one who knows his responsibilities; one who knows his role - in Wano and also the world - and not an Orochi 2.0, who was a selfish egomaniac; and one who could fulfil the goals his father had, of which he couldn't achieve... and understand the background to what led him to such goals, and I believe this answer is linked with the SH crew, like how Oden's goals were linked to the WB and Roger pirates.
Sorry for the long post. xD
Even as early as Zou, he wanted to know the Kozuki clan's history, and their role throughout the centuries.
