No matter how you look at it, Yamato has to leave wano. We saw what the people of wano did to the kurozumi family. She would 100% be hunted to death if she stayed in wano post- Kaido.
Furthermore, with her connections to Oden and the whole handcuffs plot device, leaving wano seems like an integral part of her character.
So either she leaves with Luffy or she leaves with someone else. And I for one cannot see who else she could leave with. Her being an Oden fangirl already makes her a prime candidate for a straw hat.
as for her dream and role, that will come later. If we don't see much, then I guess we can rule her out. But there is too much we don't know about her for now to say she won't join.
If I were to guess, I would say that Momonosuke joins the crew with Carrot and yamato coming along as his retainers. Momonosuke would be the cabin boy. I think this is likely as momonosuke's story doesn't seem to just end in wano. He has a special power that allows him to control zunisha, be that an ancient weapon or something else, it will be of huge significance to the end of the story. And with him being Oden's son and all, it just doesn't make sense for him to stay on wano the rest of luffy's journey, especially when he has already come so far.
Momo even has a relationship with zoro, imo similar to shanks and rayleigh. I can see Hiyori becoming the shogun/empress of wano post-kaido with momonosuke sailing off with Luffy after reading his father's journal.
this would also fulfill carrot's role. imo she also can't just disappear after wano, as Oda already spent so much time establishing her relationship with the crew.
In any case, I see more arguments for Yamato joining than not.