Chapter 1048 of One Piece, "Twenty Years," seems to be the beginning of the end. Luffy and Kaidō have both launched their ultimate attacks; the Gum-Gum Bajrang Gun and the Rising Dragon Flame Bagua. With this, the climax of the fight and the Wano Arc has become a power struggle to see who's attack can overcome their opponent's.
This sounds like a pretty standard way to end a big shonen battle, but in the context of One Piece, it poses a potential problem. A fight from the manga played out in a similar manner to this one in the anime, and not many fans were happy with it. If Eiichiro Oda isn't careful, he may repeat Toei Animation's mistakes with the climax of the fight between Luffy and Doflamingo.
To elaborate, here's how the Doflamingo fight was supposed to go. In Chapter 790, "Heaven and Earth," Luffy took to the sky above the Warlord, inflated his arm, and launched his then-ultimate attack, the Gum-Gum King Kong Gun. Doflamingo tried to block it with a combination of Spider Web and God Thread, but Luffy smashed through both of them. The impact of the King Kong Gun with Doflamingo sent him falling to the ground so hard that the earth split open, and the surrounding buildings were all leveled. The entire sequence was a showcase for how powerful and how unstoppable Luffy's attack was.
The unstoppable aspect of this scene was not translated well into the anime adaption. In Episode 773, "Attack on a Celestial - Luffy's King Kong Gun of Anger," the climax was significantly drawn out; over a minute and a half passed between Luffy's fist making contact with the strings and breaking through them to hit Doflamingo. The result was less like the instantaneous impact of the manga and more like a beam clash straight out of Dragon Ball Z.
Fans were upset by the anime's take on Chapter 790 for a number of reasons. For one thing, it was yet another prime example of Toei needlessly stretching out scenes from the manga. Not only that, but it was coming off an arc that was already needlessly drawn out, even in the manga. Whether this was meant to pad the runtime, unnecessary tension to the scene or both, fans felt like it was all a big waste of time.
Making Luffy struggle in the anime also removes the feeling of superiority that was in the original scene. In the manga, Luffy immediately breaking through Doflamingo's defense served to illustrate how powerful he was at that moment. By extending the scene so that Luffy apparently has to try harder to force his way through to Doflamingo, that sense of overwhelming power is severely reduced. This point won't necessarily apply to the clash between Luffy and Kaidō, but it matters here.
Stretching out this scene in the anime also takes away the sense of impact felt by the original. If Luffy struggles to break through the strings and reach Doflamingo, then he shouldn't have the force or momentum to knock the Warlord back the same way he did in the manga. Even Luffy's cartoon physics can't justify or account for this.
What makes all of this even worse is that it's not the only time the anime has done something like this. Toei gave a similar treatment to Luffy's final attack against Caesar Clown in episode 617, "Caesar's Defeat! The Strongest Grizzly Magnum;" not only do all the complaints about the Doflamingo fight apply here, too, but they're magnified as Caesar had absolutely no right to make Luffy struggle. As much as fans disliked the end to the Doflamingo fight, it was only part of a larger problem with Toei's handling of the anime's pacing.
The climax of Episode 733 was so poorly received that fans took it upon themselves to fix the scene. There are several edits online that shorten the scene to make Luffy's punch seem more instantaneous like in the manga. These edits are praised as not only do they make punch seem more powerful, but the scene, in general, flows better than the unedited version.
Unfortunately, it seems Oda is about to make a similar mistake to Toei. The climax of Luffy's battle with Kaidō bears a striking resemblance to his battle with Doflamingo, especially how the anime portrays it. Such similarities include Luffy hovering over his enemy, throwing his literal biggest punch yet, and struggling to get through said enemy's defenses. Depending on how the fight plays out, more similarities could continue to pile up.
Of particular note is the time it's taking to actually hit Kaidō. The punch started on page 7 of Chapter 1048. By the final page 17, it still hadn't reached the Emperor. It will be at least another chapter before Kaidō actually takes the blow, maybe longer. However long this punch is supposed to last, it's apparently going to take a while.
The climax of this fight looks like it will be even more drawn out than the climax of the Doflamingo fight. Unlike that fight, the struggle for Luffy to land his punch is actually happening in the manga. However this all ends, the anime will have to make the clash drawn-out because it's canon to the story.
This could go one of two ways. On one hand, this climax could end up precisely like the anime version of the Doflamingo climax. If that happens, then the time it takes for Luffy's punch to reach Kaidō will feel like needless fluff that makes the climax drag on.
It's also possible that the stretched-out climax will somehow work in the context of the Kaidō fight. It makes sense for Luffy to struggle in this fight as he's up against the world's strongest creature. Here, the tension and drama might be deserved, so maybe the finale will be genuinely satisfying once it eventually happens.
Whatever happens, the Wano Arc is locked in for a long climax. Whether it turns out alright or just like Dressrosa will be up to Oda's writing. However this climax turns out, Toei will probably find a way to make it seem even longer.