Haven't been on this site in quite a while. did briefly poke my head in the previous version of this thread early on in Wano though to see what characters people were discussing.
And have now briefly skimmed this thread to see who's on people's minds.
I've been thinking a lot about who could be the next/ last Strawhat so feel like sharing my ideas here for the heck of it.
I used to be heavily of the belief of the "Mugiwara no ICHI MI" 13 theory. but given how late we are into the story now, unless the last 3 strawhats join all at once, it feels like we're only getting 1 more crew member.
At best, if Vivi joins and Carue comes along with her (though they don't seem to be together right now) then Carue and Zues could be considered crewmates bringing the number to 13 total with 11 actual crew members 1 pet and 1 servant/living weapon.
Prior to the ending of Wano I was a big supporter of Carrot, but now feel the ship has literally sailed for her (unless she's stowed away and just hasn't revealed herself yet,lol)
I'm iffy on whether Yamato is going to make a comeback, it feels like their story is unfinished, but also like there's not time left for things to progress in Wano/ with Momo enough for Yamato to decide "now I can go join Luffy" I can definitely see Yamato, as well as Momo and Kin'emon joining in for some future major battle as "honorary strawhats" So I see Yamato as more of an "eleventh hour" Strawhat who is part of the crew for the final final moments of the story, as opposed to the actual eleventh Strawhat
As for the characters that I feel have actual potential to join the crew either on Egghead or just after it.
Vivi: yes, she is queen of Alabasta, yes her goals align better with the revolutionaries than they do the Strawhats. and (as far as we know) she isn't much of a fighter, and would be down with the weakest Strawhats, if not below them. which is not something we need this late in the game when we're going up against the big leagues. but, she's already an honorary Strawhat, she has had plenty of development, she's relevant to the story. and as we now know, she carries the will of D.
Even if she isn't the next/final Strawhat. she's at least going to be temporarily re-joining the crew and traveling with them, acting as a part of the crew while she does.
Lilith: I'm iffy on this. but she's seemingly had more attention/ screen time than any of the other "punks" even the apple man himself. and seemed really excited for the chance to go out to sea. unless she somehow gets cut off from Punk Records and loses some degree of her smarts, I feel like having her, or any of the punks on board invalidates Franky a fair bit. but then. he's a shipwright, not an inventor, so who knows. Usopp was the one who repaired the ship before they got a shipwright, maybe Franky was just our inventor until we got a Punk?
Plus if a punk joins, it's basically guaranteed that the Sunny will become the "giant robot of dreams" that the Punks seem to want to build. would be pretty cool to see Robo-Sunny, piloted by either Punk, Jimbei or Franky. fighting San Juan Wolf.
Smoker: I'm really nor sure where they're going with Smoker as a character, but they're keeping him around. so, I guess it's possible that after all his interactions with the Strawhats, and butting heads with the world government/ marines. something might eventually lead him to joining the crew instead? maybe? I don't know, I feel like Oda could make it work, but I'm not sure.
Stussy and/or Kaku: eh, Stussy has barely interacted with the crew yet. and Kaku, while he didn't immediately turn on Punk and the crew like Lucci did, there's little to suggest he's gonna abandon CP0
Bonney: Bonney seems to fit the crew's energy well. but her devil fruit and fighting style aren't really that impressive, and her story is so tied to Kuma that I feel she's ultimately going to be heading down the path of being a revolutionary. at best she'll travel with the crew for an island or 2 like Vivi, Law, Carrot and Momo.
Kuma: Kuma has had a long and mysterious history, both with the Strawhats, and all on his own. A Tyrant King? a Revolutionary? A Cyborg loyal to the world government? sparing the Strawhats at Thriller Bark, saving them at Sabaody. then protecting the sunny for 2 years as his last act of free will before becoming a full war machine. it's impossible to say that there isn't something going on with him that still needs to be revealed, or that he's not going to be super important to the story, especially in Egghead. as other people have said in this thread, his devil fruit, and the fact he spent 2 years protecting the Sunny would make him a good fit for a "ship's guard" role on the crew. but, at the same time. I can't really see Kuma interacting with the crew and fitting into their dynamic. unless getting his memories back will somehow change his personality and make him a perfect fit for the crew's energy... he'll just feel like a weird inclusion.
Plus I feel like with everything he's going through now, He's being set up to die this arc. (it's possible he survives and instead re-joins the revolutionaries too though)
So even though he'd be a great ship's guard. I feel like he's not really fit to be a Strawhat
That brings me to my crazy crack theory.
What OTHER character is present on Egghead right now. has a bodyguard/protective job. and has touted having amazing defence? that's right. my crazy pick is none other than Sentomaru. He's now branded as a traitor to the world government and allied with the Strawhats to protect Vegapunk. Sentomaru is extremely loyal to Punk, so If he told him to "help the strawhats" I can fully see him just showing up on the Sunny after they leave egghead and inviting himself onto the crew, Robin style saying something like "old man punk told me to help you guys, so I'm joining you"
If Kuma dies this arc, it's even possible that Sentomaru will inherit his devil fruit. he already fights with palm strikes like Kuma. so adding the paw paw fruit to that would fit well. and then he can have the 2.9 devil fruit to fit that old theory. and his defences would be even greater with the Paw Paw Fruit's repel abilities.
So then he'd be able to act as a bodyguard/rear guard/ ship guard of the crew. teleporting himself into the fray, protecting the weaker strawhats, protecting the sunny, etc.
The only issue I can see is that he wouldn't leave Vegapunk behind. unless Punk dies this arc too. or for some reason Punk decides it's better for Sentomaru to travel with the strawhats while he joins the revolutionaries or something, I can't see him leaving Punk's side. but, for now. outside of Vivi, he's my top pick.
Crackiest of Crack Theories: It's Ghin. Ghin is the last crewmate. after all, he said he'd see them again on the Grand Line.