I thought Sana's skin tone was wrong, but it's just the scan (or print?) quality. Looking at Yamamoto's Twitter banner (
link), the color is the same as the Sugimori art.
Yamamoto posted more drafts for the cover:
He said the composition was basically decided, but he hesitated because "Tyrunt is standing out more than the protagonists", "X is small for the third volume in a row", and "I want to include Parfum Palace", so he changed to the final one. We can see that the Flare Grunt is already making that face here.
About the Diancie scene, the dialogue doesn't seem to be important. They're foreshadowing Green and connecting to ORAS, but other than that, nothing important.
That seems to be on purpose. They're really advertising the
Pokémon Fan chapters on social media.
On volume 55's Amazon page, there were some people (well, I at least remember one) complaining about how volume 55's XY part was just a rehash of the XY volumes, and how they were going to stop buying. Putting the
Fan chapters right at the start allows them to have something new on the book previews to show casuals "Hey, this isn't just a rehash, you have a reason to buy this".
I'm pretty sure volume 58 will start with the Diancie chapter, even though 57 ends in the middle of a battle. In fact, I'm now fully expecting all of ORAS and SM's full volumes to start with completely new chapters that didn't even exist before, and that might be PokéSpe model going forward. Actually, when they first announced "XY in 2020", maybe they were planning to have the Hyper Training chapter and/or Eevee chapter in volume 55, but the B2W2 finale grew bigger than they expected? Who knows.
So, we're now missing two
Fan chapters, the Diancie one and... What else again? I don't remember. Or was the Diancie story a two-parter?
If the Diancie thing was a two-parter, volume 59 might already begin with new content. You know, maybe the reason the volumes are coming out so long apart is so Yamamoto has time to work on new completely new chapters for not just XY, but also ORAS? Kusaka probably already has an idea on what he wants to do for extra story content for both of those, maybe even Alola.
And volume 58 will have the one scene I'm really looking forward to: The third Pokédex. Is it still going to be destroyed, or will it be picked up by a Grunt or one of the scientists, and who knows given to Matiere (Emma)? That one scene alone could finally tells us whether Kusaka really intends to keep Pokédexes exclusive to characters with game names, or if the name tradition is now a bust. It could perhaps give us hope that Sana, Tierno, and Trova might eventually get Pokédexes and be acknowledged as main characters, and who knows the Unova Rivals get Pokédexes whenever we get BW remakes (or if we get an USUM arc. There's a theory in 5ch the resonance sound might be what reveals Lack-Two's disguise), and most importantly, after being snubbed in 2005, Mitsuru (Wally) could FINALLY have his own Pokédex in ORAS!!
February 26-28 can't come soon enough. Wait, 26 to 28? Holy crap, volume 58 might actually come out on Pokémon Day! Just imagine the potential boost it could receive from being a Pokémon Day release. Heck, if the third Kalos Pokédex is not destroyed on volume 58, we could perhaps see a defining tradition of the franchise's most popular manga being changed
on the franchise's 25th anniversary. A restricting tradition being updated during a major anniversary? Please Kusaka, do it!
It wouldn't be the first time a mistake like this happened. FRLG had Green's Porygon2 listed as male.
But I think it's a retcon. Male Dex Holders rarely have female Pokémon at all, and no Starters so far, so I don't think they would accidentally label Salamè as female. Now, why would retcon this though? Hm...
Okay, hear me out. We later have Green and his Charizard showing up, right? And with Salamè, we now have TWO Charizard. And Green's Charizard is male. If Salamè is retconned into female, we now have a male and a female.
You can see where I'm going, right? What if Salamè is going to lay an egg, with Green's Charizard being the father?
Sounds crazy? Maybe. But think about it a bit. For the first time since Gen 3, there's a chance of the name tradition being broken and us having Dex Holders not named after the games. Manabu (Marvin) having a Sobble and tagging along is a big indication that he might get a Pokédex (and who knows, might be the real SwSh protagonist instead of Soudo), and in that case Sana, Tierno, and Trova might get Pokédexes because they're Rivals in the games.
Every Pokédex Holder has a Starter Pokémon, except for Whi-Two who is in a sort of limbo because of Unova weirdness. So, if X and Y's friends get Pokédexes, they might also obtain Bulbasaur and Squirtle, with Salamè's offspring completing the trio. Yeah, it would have been better if one of them got Salamè to get the true trio, but that ship has sailed in 2014. I don't see Kusaka giving the one Charizard that can go Mega X to someone other than X, and having two Charizard among the kids' teams can allow for all Kanto Starter Megas to be usable by them.
And who knows, maybe all of Professor Platane's Kanto Starters are female, and the Bulbasaur and Squirtle will eventually become the mothers of the Isle of Armor's Bulbasaur and Squirtle.
Or maybe Kusaka just wants the Kalosian Kanto trio from the Kantonian Kanto trio by repeating what he did in BW with the two sets of Starters where one was all-male and the other is implied to be all-female (Samurott's gender was never revealed).
But the Salamè Egg Theory makes me think about Delphox. I have been thinking for some time that Delphox would end up with Sana because it was blown away with Furfrou, who also protected it after Team Flare's defeat, and also because she has one Starter in the games. But now, if Matiere is actually given the Pokédex Team Flare found, I'm thinking she's the one who will end up with Delphox, while Sana gets the new Charmander.
Remember how in the games Sana breeds her Starter and trades the offspring with the player? IIt would be a funny inversion of the games if instead she is the one receiving the offspring of X's Kanto Starter.
The Salamè Egg Theory also reminds of how Emerald's team seems to be built basically for the epilogue Sinnoh babies foreshadowing that so far has gone nowhere other than a very vague implication that Diamond's Munchlax is the baby the two Snorlax.