This theory regards Moriah and his part in Blackbeard Pirates (assuming he joins).
Kaido wants to die. He has been written as an unkillable creature. I personally think this is foreshadowing that Kaido will die. There has been many theories around Blackbeard obtaining Kaido’s devil fruit (if he even has one). But I don’t think that’s the extent to which Blackbeard wants to use Kaido.
Moriah has a very interesting and powerful ability, and I don’t think it’s just random that Oda is adding Moriah to the crew of Blackbeard (arguably the final boss of the series). Oars I feel is a very underestimated example of how strong Moriah’s power is. And I think Kaido will become the next Oars.
After this last chapter I personally believe Blackbeard is going to show up last minute to Wano like in Marineford and finish Kaido off. I think he’s then going to take Kaido’s power and then use Moriah’s power to resurrect Kaido and add the most powerful creature into his army.
This would be something both Blackbeard and Moriah would be interested in doing, because Moriah hates Kaido, and having him serve as his own zombie slave would probably gratify him.
But yeah, what do you guys think? Each time we see Blackbeard, he and his crew grow exponentially more OP. And there’s nothing more OP I can think of than acquiring the strongest creature in the series into your crew. I can’t think of another reason as to why Oda would add one of the weakest villains into Blackbeard’s crew out of nowhere, unless Blackbeard has an extravagant plan to utilize his ability.
*Theory by pegilly