"The expression he who laughs last, laughs best is a saying that means the final winner will have more glory than someone who was winning in the beginning but ultimately lost."
Considering current events within the manga, the meaning behind this statement and it being tied with Zoro exclusively leaves little room for interpretation.
In regards to the "final winner" part of the saying, the only other person it could refer to other than Zoro would be Luffy but this isn't nearly as sound as it being Zoro instead, considering the fact that Zoro was the one who has the saying written directly on his back, as well as how he was seated next to a tombstone with Kaido's vivre card number crudely scribbled on. This same vivre also mentions on Zoro's purpose within onigashima is to slay an oni which would of course be Kaido. Interestingly enough, Luffy actually more concisely fits the latter portion of the saying, that being the "someone who was winning but ultimately loss", which admittedly, is yet to truly occur but considering Luffy's awakening and his already outstanding performance against Kaido pre-awakening, it stands to reason that luffy will return to the fight, give Kaido the business temporarily, but ultimately fail thanks to his existant injuries, additional injuries from what would be their latest scuffle, or both. All of this in tandem with the fact that the cover page in question takes place in a graveyard which naturally has the theme of death, much like Kaido himself, makes for a simple conclusion that any able minded person should be able to come to...
Zoro is the one who will Kill Kaido