I’m of the opinion that Oda has multiple potential reveals/endings in mind for his arc and makes his mind up closer to the finale of said arcs. Oda had it in the works as a possible ending for Onigashima but ultimately wanted Gear 5 to have the W.
Chap. 1023 is named after Zoro’s resemblance to Ryuma, frequently the samurai mention needing to kill Kaido, Luffy does not kill yet Zoro does.
It was a legitimate theory.