I don't think Big Mom will be defeated in any traditional sense, but it would be weird to travel all this way and not weaken her in some sense. Considering how many forces is being gathered to go against Kaido, I don't think it will be likely that Big Mom will be fought against face to face when the Strawhats is lacking half their crew in Whole Cake Island. I think Sanji will be rescued, and the SHs will narrowly escape with the poneglyph, and they will leave a big enough mess so that Big Mom will not have the ressources to bother with her revenge on Jinbe/Sanji/Luffy.
Anyways Kaido, Blackbeard and Revolutionaries are kind of occupied now, and the Marines have the Reverie, Akainu/Fujitora problems and reworking the shichibukai system to focus on. So the only left is Shanks, which is left for another time. This means that any more forces will be introduced now, and if any chaos is going to happen, it is going to be because of Capone Bege, Vinsmokes or internal conflict in the Big Mom familiy. The SHs and Bege are of course going to be the jokers in the story.