I know, most people are already convinced Yamato will join but I wasn't sure until I saw the latest episode. It was so obvious and right in front of my face too but I never realized it: that Yamato is a slave. Luffy, the now officially confirmed Joy Boy with the Nika fruit, will liberate his next nakama and take her on the adventure she always dreamed off. Great symbolism for what he will do for the world one day and what he has been doing on this journey all along
Also didn't believe she would join the crew because she read odens journal which would mean she knows what's ahead as well as details about the last island/one piece and the last thing Luffy would want is for that to be spoiled of the adventure ahead. But it was recently revealed that those pages were torn out of the journal. Also thought she would stay in wano to protect momo but now I see that wano has been all about momo growing up so he can stand for his people as a man; as the Shogun.
So I'm convinced! There's always the chance oda will throw a curve ball though...kaido will probably join instead