Okay, look, I know this isn't "canon", BUT....it's also the only other story One Piece has done featuring dragons of any kind. Even if these aren't exactly "traditional" dragons, being feathered. And I'd never seen it before, since I originally watched the 4Kids versions on TV, which skipped it, and Toonami kept skipping ahead. So, this was actually the first time I've ever seen these episodes.
Plus, this is technically the final arc of the first season of the anime. This is the first filler arc EVER in the anime! And part of me kind of wonders if Oda didn't worry that he actually wouldn't GET a season 2. And I just have to wonder if Oda didn't share a few little details about what he had planned for a ending, if he ever had to end it early. At the very least, I kind of wonder if Oda didn't give the anime crew a few notes about how HE would end up treating dragons later, if they ever showed up in HIS version of the story. They've never even hinted at that. In fact, they've actually said this was originally the plot for a scrapped movie, but never anything involving Oda himself. Still, it's possible a few of his endgame ideas got in here.
Because...there's some REALLY odd "firsts" in this anime filler arc.
This arc sees the first appearance of Luffy using "The Voice of All Things", even if it's not called that, since he can understand what the dragon is saying.
This sees the Marines looking for a immortality elixir...kind of like Law's immortality surgery.
This arc ALSO sees the first appearance of a "Mythical Zoan" Fruit, with the Kamaitachi Fruit. Now, this might be referring to the type of WIND rather than the Yokai, but it's still odd. And Erik, the Kama Fruit user, even kind of feels like a stand-in for the Gorosei in some scenes. He's a competent fighter who's serving under a big fat entitled jerk (Nelson Royale) who looks a LOT like the Celestial Dragon Charlos. Erik even has the same Shachihoko/"carp" haircut that the Celestial Dragons do, YEARS before they showed up in the manga.
And again, there are jokes here which, in retrospect, feel like foreshadowing the Kamabakka Queendom, YEARS before they showed up in the manga.
The old dragon keeps looking to the sky and birds. Which KIND of feels like foreshadowing Skypeia.
Battleship Island is called that because it literally looks like a battleship...which feels like seeding the idea for the Ancient Weapons. Even though it doesn't turn out to be a weapon or a actual battleship.
The Marines actually use a BUNCH of ships to attack the Strawhats. Which feels like a prototype idea for a Buster Call, which we hadn't seen yet. And they use a Gargoyle/Komainu ship which MIGHT be a stand in for a Ancient Weapon or the Mother Flame.
A ocean-wide earthquake leading to a island that was underwater rising to the surface after hundreds of years. Kind of like a parallel to the Mother Flame SINKING islands far beneath the ocean in the main story. It really does feel like the whole "hole in the ocean" in reverse in this filler arc.
The inhabitants of this island are literally the descendants of a Ancient Kingdom. (Not THE Ancient Kingdom, but still).
The old dragon roaring to summon the other dragons back home is kind of similar to Shirahoshi's cries summoning the Sea Kings.
There's also a island seemingly "magically" hidden from the world, where a Ancient Kingdom lived. A Ancient mural which depicts a sun and moon. The reveal that the "treasure" that they look for here is actually FAR closer to their starting location than they originally thought.
Apis, the sympathetic girl for this island, has a necklace that actually looks a LOT like a tiny Dragon Horn from Monsters/Ryuma.
Apis has a tall pointy hat...and Imu has a tall pointy hat...that's stretching things, but I do feel like they have similar silhouettes.
It's just...interesting. And it feels like a prototype to One Piece's REAL ending soon to come.
So, does this actually lead us to anything intersting to expect from the real ending to One Piece?
Well...no, not really.
There's a old man who goes into a long, droning history of the world, which almost feels like a parody of Oda. It actually goes into too much detail, though, focusing on who's begot who. Although, it does mention some brothers looking for a "Tree that bears stars as it's fruit" which feels like it COULD be important. It might be a hint that the Devil Fruits do come from space, maybe?
And later he also says "The War Ends in the 1201st Generation". So...maybe this is hinting that One Piece will end around chapter 1201? Which, actually sounds reasonable, to me. I could see it ending within a 100 chapters or so. Oda seems like he wants to wrap this up sooner rather than later, and he's actually been pretty consistently predicting that One Piece will end in 2024 or 2025.
If we take this story as a hint, then MAYBE the One Piece treasure will turn out to be the last remaining living naturally-born dragon? Maybe we'll hear the history of the world coming out of a dragon's mouth.
And they have to return the dragon to it's birth place so it can be reborn, kind of like a phoenix. And honestly...I could see Luffy as a stand in for this old dragon. Luffy's been looking old after he uses Gear 5 lately. Maybe he'll overdo it one of these times and get stuck as "Old Man Luffy", and he'll need to get to Laugh Tale or something to recharge? And...Luffy MIGHT die fulfilling his dream. "Don't you want eternal life?!" "Once this guy has done what he's set out to do, he'll die with a smile on his face".
And it features part of a island returning to the surface. So maybe all those islands the Mother Flame shot down into the ocean will eventually be returned to the surface? Or maybe it's hinting at a return to more land to this mostly ocean-covered planet?
The Marine's end up making a wall of chains with their ships to try and trap the Strawhats. Maybe that's a hint that they're going to create another Red Line? Trying to create another "wall" around the whole world?
This is a stretch, but...Battleship Island is revealed to be the original home to the dragons that they return to every thousand years. I kind of wonder if this is hinting that the Ancient Weapons are actually spaceships that originally brought the Celestial Dragons to this world?
Nami also has a kind of...weird moment on the Hidden Island. So maybe that's hinting that Nami has a connection to the Ancient Kingdom?
And...um...Zoro actually says he's going to kill Luffy someday because he keeps messing things up for him. It's probably just a gag, but given some of the "Traitor Zoro" theories I've seen, it's worth mentioning.
The dragon homeland ALSO being like a elephant graveyard might ALSO be hinting at Laugh Tale and the One Piece being "A dream within a dream". Something's distorted about the story they know.
Although, once the story's over, Apis decides to stay on the island and have her descendants protect it forever. This kind of implies that the cycle of history won't actually be broken. Or maybe, if Apis is supposed to be a parallel to Imu, it's possible Imu doesn't WANT the cycle to end because she's protecting something.
I mean, chances are none of this actually means anything for the future of the manga. But, it'd be interesting if it did.