It actually makes More sense for Luffy to beat BigMom and Zoro to beat Kaido, reasons are
1: Luffy training on hitting without touching which seemed absolutely necessary against BM in WCI
2: Pedro lost his life because of BMP and Luffy has to take revenge on that
3: Zoro got Enma
4: Zoro was mostly depicted as Tiger, and the Ying/Yang thing is Tiger VS Dragon ( Kaido Type of Dragon )
5: Zoro is supposedly the 2nd coming of Ryuma killing the tyrant Dragon
6: The theory you might've read that Zoro's father Ushimaru Shimotsuki was also Killed by Kaido, so if thats true then Zoro has to be Kaido's opponent....
but nah everything always goes to luffy so....cant get our hopes up