After the latest chapter, I think Luffy will indeed defeat both Big Mom and Kaido this arc but with help and only after they are nerfed.
I feel like the Marines will be here, whether with Kizaru/Ryokugyu or not, and this will give Luffy the boost to win. Big Mom vs Kizaru/Ryokugyu before facing Luffy or Luffy outright teaming up with the admiral and/or Marco to take out Big Mom is also possible. BM is already nerfed from losing Zeus, a nerfed BM isn't winning against an admiral, a YC1, and a YC1 level fighter (especially since Luffy has likely mastered Ryuou).
Also, I don't doubt Kaido is going to win against the Scabbards and the Sulong Minks, but it's not gonna be easy. He'll not come out of this unscathed and this sets up Luffy & Zoro vs Nerfed Kaido perfectly.