@Deicide:
Well…
- When Yamato says he will go to the sea and become stronger, he makes it clear the objective is to return and participe in Wano's big battle later. This places Wano as a possible bigger objective than going out to sea.
- Yamato shows interest in becoming a samurai when talking to the ones in the cave.
- Kaido taunts Yamato by saying the samurai will never consider him one of their own.
- When Luffy first asked for Yamato to take care of Momonosuke, Yamato's reaction is one of doubt. "Can I...? I mean, sure h-he is my son and all...". Maybe because deep down he believes he won't be accepted?
May I be looking too deep into these moments? Maybe.
But coupled with his DF's significance and his biggest moments being related to Momonosuke or declarations of fighting for Wano, I sure won't discard the possibility that deep down Yamato dreams of becoming a samurai, and Momonosuke not only making him one, but making him "Kozuki Yamato", may actually supercede his desire to join Luffy in the end. That path is still open in the story.
What I mean is that the story is not really going straightforwardly towards Yamato joining the crew. It's instead running around the issue and avoiding it on purpose. Maybe it remedies this in the epilogue, but it can also go in another direction.
I think Yamato's goals (stated and unstated) can be broken down into three things:
- He wants to free Wano from his father.
- He wants to be accepted by Wano's samurai.
- He wants to go out to sea.
You are framing goals #2 and #3 as somehow being in conflict with one another. That being accepted by Wano's samurai implies staying in Wano, while going out to sea necessitates leaving it. That Yamato will ultimately have to choose which is more important, and set the other aside.
But fundamentally, I do not believe that is the case. More to the point, I don't believe that's how achieving one's dreams in One Piece operates.
Yamato's words in the short flashback we got seem to state that he wanted to go out to sea from more or less the start - implicitly to get stronger in preparation for the final battle to take down his father 20 years later. As we know, the explody-cuff situation prevented that. He reiterated that desire with Ace, with the same result. And he reiterated it with Luffy, with the result being that his shackles were finally broken, but it was too late to go out to sea before the final battle with Kaidou. Yet he still states he intends to go out to sea with Luffy once the battle is over.
Now on some level I think you are right. I think Yamato believes that, at the end of the day, he will not be accepted by Wano's samurai, and that may factor into why he intends to leave once the battle is over - that he, as "Kaidou's son", wouldn't be welcome if he wanted to stay. Given what Wano did to the Kurozumi clan, he may have good reason to think so, but clearly, that's ultimately a non-issue - once all is said and done, Momonosuke and the Akazaya will welcome Yamato with open arms.
You claim that because Wano's samurai (or the only ones that matter, at least) will accept him, Yamato will choose to stay, discarding his dream of going out to sea as something unnecessary.
This is where we disagree. I think that because Wano's samurai will accept him, that Wano will become the home Yamato can return to once his adventuring days are done, and this allows Yamato to achieve all of his goals, even the ones that seem to conflict with one another. One Piece isn't a series about compromising on your dreams - it's about doing the impossible so you don't have to.
Nothing we have seen from Yamato indicates to me that his stated desire to go out to sea is somehow secondary to his more implicit desire finding some manner of acceptance from the people of Wano. He wants to travel, he wants to see the world, he wants to go on adventures - all of which have been denied to him for the past 20 years due to his imprisonment on Onigashima.
And beyond that, Oden's journal gave him a glimpse into something bigger - the journey of the Roger Pirates, what they'd hoped and failed to accomplish, and what they'd left for those who would follow in their footsteps. Yamato wants to be a part of that, and choosing not to sail with the man who will become the next Pirate King in order to stay behind on Wano ensures that he will never be.