Stop killing my favs..... those trash ass antagonist never die but main characters will die...
The problem is that there are Hints that she might not join, and tbh only thing i can see preventing her from doing so is Death.
1. Luffy's DF = 5 & 6 --- Robin's DF = 8 & 7 --- Brook's DF = 4 & 3 --- Chopper's DF = 1 & 10, this only leaves Room for another DF User with Number 9 & 2 (Such as Kuma's DF or Kin'emon's DF). But Yamato's DF doesn't fit this Pattern & would ruin it if she joins (And trust me, Oda is crazy about Numbers)
2. Yamato's Will = Momo's Will = Oden's Will, they are exactly identical in Purpose, the Story has always been about "Inherited Will", such as Luffy inheriting Ace's Will who inherited it from Roger/WB, Luffy & Ace couldn't Co-Exist, just like Yamato & Momo cannot Co-Exist. (Pedro is another Example of a Character who died & Carrot inherited his Will ... etc)
3. Before any Crewmate joins, Oda shows their Unique Skills that will define their Role on the Ship (Franky, Robin, Chopper, Sanji & Brook were Introduced as Shipwright, Historian, Doctor, Cook & Musician respectively and we also saw Jinbe's Skills as a Helmsman during WCI, and Usopp's Sniping Skills, and Nami's Navigational Skills ... etc), but when it comes to Yamato, Oda didn't bother showing us even a single Unique Skill of hers (Vivi for example had this Problem too & she ended up not joining)
4. Each Straw Hat have a Backstory with someone they really cared for, who either died or had a traumatic experience with & then they Inherited their Will/Dream, such as Zoro/Kuina, Nami/Béll-mere, Usopp/Banchina, Sanji/Zeff, Chopper/Hililuk, Robin/Saul, Franky/Tom, Brook/Yorki, Jinbe/Fisher Tiger, but with Yamato, there is no such Backstory, no such connection, she says she is Oden but she never met him, and there is already one who inherited Oden's Will & have a Backstory & Family Bond with him, it's Momo, so as i said again, these two Characters cannot Co-Exist. (For example, when Oda wanted to Draw two Characters who inherited Wills in Fishmen Island who are Jinbe & Shirahoshi, he created two Inspiring Figures for them who are Fisher Tiger/Otohime)
5. She was introduced during the Raid & was completely absent from entire Wano Side of Arc something completely unusual & doesn't fit Future Straw Hats. Not to mention that she has Parallels with Ace, and so far most Fandom has already noticed that Pre-TS & Post-TS are like two sides of the same Coin, so it's highly possible, that just like we had Death of WB/Ace, we will now have Death of Kaido/Yamato. Especially since she said she is Oden, as if she is telling us, she might Die just like him
6. And also, she was introduced as having Daddy Issues with the Villain, but she rejects his Will & sides with Alliance, as simple as that. It's not like others SH who had real Villains & a convincing Backstory with them. And also she isn't drawn among Oda's Early Straw Hats Sketches, nor did he imply there is another Crew Role that needs to fill. This doesn't prove he can't create New SHs, such as Robin & Franky, but it doesn't help her case still
Again, i'm not against her joining the Crew nor do i care if she dies, but this is a Very Major Battle with expected Death in it from Alliance Side, Yamato joining the Crew seems too obvious that i believe Oda is preparing a Plot Twist & when you really think about it, she truly seems like an Odd Straw Hat, and too much connection with People who have Mark of Death (Kaido, Oden, Ace) & literally no Ally. She is "The Nameless Fighter" (That's why Oda made her learn this from Samurai in this Chapter) & combined with her Mythical DF, it seems she will give birth to New Wano Legend