Big Mom is falling in Wano. Along with Kaido as Wano arc is all about the new era surpassing the old. The remnants of Rocks Pirates crew both go down in this arc. It has even already been foreshadowed.
Oh sure, that outcome is definitely impossible lol. If a generation of pirates could take down both Yonkos it definitely won’t be the “Worst Generation” right?
There is no reason for Big Mom to remain as a central antagonist after this arc as she will just be a remnant of an era that will end in Wano. Luffy will be the downfall of Kaido, Kid will be the downfall of Big Mom. There is a reason that Oda has set up beef between Kid and Big Mom going all the way back to Fishman Island when we find out he’s sinking her ships.
Even more beef gets setup between them in Udon where we find out that Kid stole something from her territory and injured her Commander.
Old Era: Kaido and Big Mom
Current Era: Shanks and Blackbeard
New Era: Luffy and Kidd
After Luffy and Kid each take down an old era Yonko respectively, the next arcs will focus on Shanks and Blackbeard. The new era will have conflicts with the current one. Notice how Luffy has beef with Blackbeard while Kid has beef with Shanks, those two will be Luffy and Kid’s next steps respectively.
Oda keeps setting up conflicts between Luffy/Kid and the Yonkos for a reason. Kid taking down a Yonko in the same arc as Luffy would also do a very good job at delivering on Kid’s hype as Luffys rival. If Kid is going to be relevant going forward (which he will be) he must rival Luffy in some way this arc, and beating Big Mom is the obvious way.
Now Kid might not kill Big Mom, but do believe that after Wano Big Mom will lose her power/authority and the newspapers will recognize Eustass Kid as the one who was her downfall. Call it payback for the false rumors that was spread about her taking his arm and punking him
*Theory by ReggieZoldyck21