We come to the end, so it should be fast.
I can see Luffy n Kata vs Big mom Not in the way of defeat her, but to make her drop dead herself including solve the elbaf-caramel storyline. Such as: Luffy n Kata (who already stronger than WCI feat) show their CoC combo to demorale Big Mom.
- Luffy who want to beat her
- Kata who ashame of her mom, "lets not again mom, we have enough, lets back"
But big mom redeem herself, then hearing the story of elbaf, into give up her soul to someone 'kinda like Law df Immortality". So, Fishman Island is Luffy's, but WCI is Katakuri's.
Fishman Island, Sanji-Germa Niji+Yonji, Katakuri the rising Emperor, Elbaf Ally, Usopp Story are Wrapped up in a single short Arc. (Of course including a glimpse of Vegapunk, Shanks as the bonus)
But again, we might just read a Cover story of Elbaf.