Why Big Mom Won't Die in Wano:
1. Big Mom's words upon her defeat: "Don't you think that this is enough to kill me."
2. Kaido's debt to Big Mom, and this debt is mentioned many times, the latest of them was in the previous chapter, which means that Oda is planning something about this debt.
3. Kaido's falling next to Big Mom is not in vain, something will happen between them, especially with regard to the debt between Big Mom and Kaido, Oda has brought them together so that Kaido pays off his debt.