No. She doesn't fit. Not thematically, aesthetically, or narrativelly.
The entire setup of wano was about the pirate-mink-samurai aliance specifically fighting kaido & orochi's forces. It's why I don't believe the strawhat fleet is coming either.
Big mom is here for the same reason the whitebeard pirates aren't here, to raise tension.
Chapter 979 seems to indicate the kaido-big mom alliance is not istablished yet, but need to be announced and acknowledged by both parties to be valid.
Why should the big mom pirates fight to clean up kaido's mess in his own territory ? and why should the samurai who have been waiting 20 years for vengeance be fighting strangers who have done nothing to them as apossed to the people who have humiliated them?
The narrative of wano by itself is big enough to be the most important post time skip arc, it doesn't need marines or revolutionaries or vegapunk or another yonko to be important.