It's just obvious that the alliance isn't capable of winning against Kaido and her at the same time, plus no antagonist is ever defeated while most of his/her crew and most important subordinates is absent of the arc and she still have her unresolved issues with the Giants and Lola.
I honestly believe Big Mom is going down here, one way or the other. I don't see Oda bringing her as an antagonist for another arc as well, especially considering how long ago her conflict with the straw hats started without still being resolved. Her name has been tied to that of Kaido since forever, since Thriller Bark. I see them falling together as well.
I don't think that he would have brought her to Wano and make her stay the entire arc if he was planning for her to be defeated somewhere else.
Oda has also established a trend where when the strawhats arrive on an island with a special race, those guys welcome them beacuse they are already in their debts. In Fishamn Island, the Fishmens were in debt with Luffy for saving one of them pre timeskip. At Zou they were welcomed as well because their prior actions made Jack leave the Island.
I believe that it will be the same for when they arrive to Elbaf. The Giants will welcome them and be in their debts because they were the cause of the fall of Big Mom.
Plus, Oda has still to focus on the two most relevant emperors as well, Shanks and Blacobeard.