Hmm, seems like my #254 post is in this thread after all.
I have waited patiently since February for some confirmation on Shirahoshi joining, ever since I got banned for suggesting, that Shirahoshi doesn't have to be weak, that cowardice is not the same as weakness, and that she might have inherited or been taught some awesome fighting powers. (I even suggested Shirahoshi summoining Sea Kings over here, though that was still a very unrefined argument, and I think she could fight Wadatsumi)
But the latest chapter has me pretty worried.
I mean we have Otohime dying, without some personal last words to Shira, in order to motivate her, to follow her dreams, and without Shira making any emotional vows to do so. That just doesn't work for a future nakama.
So unless Oda can fix this in the next chapter, I would say her chances of joining have dropped below 50% for the first time.
Everything else went pretty much as expected. I mean Otohime teaching Shira about the islands above ground, and her speeches about them getting to know all humans, not just a small fraction of them. And of course Otohime's crying about the children getting to go anywhere they want, not just Sabaody Park. And her bravery to leave FI on her own, to visit Mariejois. And of course the legend of Shira following a man to change the whole world, not just FI.
All of this could indicate Shirahoshi leaving FI and travelling around the world with the SH's, to follow Otohime's ideals and become a symbol of hope for her people, just like her mother. (not necessarily of course)
On the whole size issue I think most people still underestimate the true dimensions of the Sunny. Here and here and here you can see, that Shira is about the size of the Sunny's Lawn Deck. (even with Oda messing up perspectives) I think Franky would be able to modify the Sunny a little, to provide a comfortable living space for Shira, something that can be changed back in the morning. Perhaps the Lawn Deck could be turned upside down to provide a bed for Shira, or the mast could open up into a large tent. (I'm not that creative)
I think it's wierd that people still underestimate Oda's ingenuity after all this time.
And of course she would attract a lot of attention. I mean she is the friggn legendary mermaid princess. But it's not so much, that it would make the other SH's look insignificant. She would rather make the whole crew look more awesome. And Robin and Sanji would still be able to sneak around undetected, while Luffy &co would march in like always, smashing through any walls, that are in the way. (I see no big problem with Shira moving around on Thriller Bark, Water 7, Skypiea, Alabasta, Little Garden or any other island we have seen just like with FI)
I think it is stupid, that people still believe mermaids to be disabled on land, even after seeing the King, Princes and Aladdin moving around just fine, and Otohime shooting around like a bullet.
Shirahoshi is not a leader of her people, after being locked up for 10 years. And now we know, that she has a much bigger destiny. She is now free to follow her heart, and Luffy became the symbol of that freedom by helping her get out. FI has other protectors like the King, Princes, Jinbe and the NFP, who all feel very responsible for protecting and leading the people, and who wouldn't just leave on a merry journey around the world. But this doesn't apply to Shirahoshi.
Of course her joining the SH's could strain relationships between FI and WG, but not more than Fisher Tiger attacking Mariejois, Whitebeard's death or Jinbe quitting the Shichibukai. At least not at first.
On the other hand Shirahoshi staying at FI would be much more problematic. I mean she is like the most valuable slave and hostage, to take control of FI. And the WG wouldn't ignore such a major threat to them, like Shira's power. She might be able to defeat an attacking Buster Call with her Sea Kings, but not without destroying their new home as well. This will be very obvious at the end of this arc, after she destroyed FI, and she wouldn't want to keep putting her people in danger like that.
She will become the most hunted person in the world, much more than Robin, and her joining the SH's may be the only way to be safe and gain enough confidence, experience and strength to defend herself against anyone.
Perhaps the WG thought Otohime had summoned the Sea Kings, and that is why she was killed. Shirahoshi being responsible for her mother's death would certainly add to her determination in the future.
But for now we need her making a declaration of her own dream, and the determination to keep fighting a strong opponent, even after she is injured. Before that all bets are off.