Yeah, this
Kaido‘s like Whitebeard, he needs to die for the series to move forward without having him hanging around in the background like Chekov’s nuke. His story has been leading to him dying since his attempted suicide introduction. Big Mom can be written out with amnesia or some shit, Shanks, Dragon, Blackbeard, Sakazuki, they should all be EoS characters anyway.
And the only two characters that are currently on Wano and seem likely to be characters Oda would let kill Kaido- given how rare death is in the series and how important a character he is- are Zoro and Big Mom. And it doesn’t look like Big Mom is likely to try and kill him as things stand.
If Blackbeard shows up, or Sakazuki, or Shanks, or even Dragon as a truly wild guess, then that would change things, but other than them there’s no one who stands out as a potential killer of Kaido.
Oda won’t let Luffy do it. Kid and Law haven’t been important enough. Momo is still mentally a child. Hiyori hasn’t been that relevant. Hard to see him letting Yamato kill her father, no matter how awful he is. Marco, nah, not relevant enough. A Scabbard? Has the reason to kill him, but can’t see Oda picking one of them over Zoro. Orochi? Too weak, should be dealt with separately from Kaido anyway. A CP-0 assassination? Don’t think they’ve been built up enough for that. Even with Luffy being the one to beat Kaido in a fight, killing him is still something that will be impressive, given how everyone has failed to do it so far.
Zoro’s got all the symbolism from Ryuma and Oden to back it up, that’s why he’s the current, by a distant, best bet. Especially with Oda starting to bring Zoro being a Shimotsuki back into the story now we’re at the end of the arc.