Gotta say, I fundamentally disagree about this. I actually don't take Kaido's title
as serious as maybe some others do on this forum, and also entirely believe Luffy will have his solo fight against Kaido. Maybe you see where I'm coming from after hearing me out:
1. The first thing that makes me doubt the entre veracity of Kaido's title is the fact that Kaido and Big Mom are essentially considered equal by all accounts. Their clashes, the fact they fought for hours at a stalemate. The sheer confidence in Big Mom in potentially killing Kaido (and vice versa). And finally just their equal stature next to each other this whole arc just entirely establishes the idea that they are effectively equal, which already hurts the idea that Kaido's title of WSC is exclusive to mean he's the "Strongest Pirate".
2. Secondly, this page from 1001:
Not only does he not have Big Mom here (someone who has been pretty much been his contemporary for decades), he's essentially questioning if Luffy could reliably fight him at that point. Only 5 other men are on here, including Shanks. This brings me back to the point of "Strongest Pirate". Rocks, Oden, Whitebeard and Roger are dead. Shanks is not. This effectively means that Shanks is as just of a viable threat to Kaido or Luffy. Luffy defeating Kaido does not lower this ideal that Shanks and even Blackbeard are weaker than him. Hell, Blackbeard is growing virtually the same way as Luffy is. As Kaido has said, we don't know "how far their ceiling will go".
3. Relating to the picture above, Luffy is the sole focal point here. Not Zoro, Killer, Kidd or Law. Yes, I get it, they have all hurt Kaido in some form, but in typical Oda fashion, he entirely and exclusively highlights Luffy
where it matters. This is something that has been consistent in the 2 decades the manga has been serialized, and I don't expect it to change at this point.
4. Its just entirely clear to me that Shanks and Blackbeard are on a whole other level of relevance, importance and likely threat level than Kaido and Big Mom. Oda decided to tackle Kaido and Big Mom first, not Blackbeard or Shanks. This should effectively tell people that regardless of what happens this arc, they will be entirely more viable threats than Kaido and Big Mom.
5. This also makes it obvious to me that even if Kaido is defeated by Luffy only, this wouldn't even include people like Akainu or Im because they are not pirates, nor do we truly have comparators to show us that they are weaker or stronger. Hell, Im hasn't even been revealed yet.
I just think that post Wano, we are moving into an entirely different ball game with the series. Luffy and potentially Kid become the next Yonko or destroy the concept of Yonko entirely (i.e. nobody is a Yonko anymore). Blackbeard is still gaining power. Shanks is an enigma. Akainu has been stated by Oda to be on of the most powerful people in the series, specifying that if he was the main character, the series would have "been over quickly". Im is nothing until we know more.
I hope this gets my point across. I think we take Kaido's title way too seriously for what it truly is: An overbearing confidence in a pirate's power, just like Perospero this past chapter riding on the coattails of his mothers power of "Yonko". We all know that the concept is being flipped on its head by the end of this arc.
This is why I think Luffy will fight and probably solo Kaido by the end, as "unbelievable" as it may seem right now.