The raid won't fail imo
- CP0 already started counting the number of defeated people from both sides, just like what happened in dressrosa with Viola. The Kaido side is overwhelmingly superior in number for the dramatic purpose until the samurais will end up winner in the end
- Oda already went too deep in the fight between worstgen and Yonkos, with Luffy and Zoro already showing the ability to hurt Kaido. It'd be pointless for Oda to make the alliance lose only for it to go back to square one once again
Imo, what i think will happen is that, act 3 will end next chapter with a cliffhanger of Kaido and Big Mom wrecking the SNs
Oda will then do few chapters explaining what's going on overseas between the marines, shichibukai, etc
Starting act 4, Oda will focus chapters on the other battles happening inside(there could be rooftop panels here and there, but it won't be the main focus), until every major player on Kaido's side get defeated one by one, showing the situation of other worst Gen members(Drake, Hawkins, Apoo) and what they'd decide to do for the remaining battle against Kaido / Big Mom
And the roof battle will resume afterwards likely with key factors like Hawkins' predictions or his card expanding one's power beyond natural limits coming in play, and leading to the defeat of Kaido / Big Mom, Luffy defeating Kaido, for Big Mom depending on Kid's role by the end of the arc