It has nothing to do with whether you're a fan of BM or not,
This Story made us always expect Villains to Return, it's that simple,
Very few Villains didn't appear after their Arcs,
Big Mom & Kaidou's Roles as Faction Representatives Ended in Wano Arc,
Oda can't bring them back now, cuz The World wd once again treat them as Major Players,
They will return when They no longer are considered a Threat on their Own,
When World Balance doesn't Exist anymore (Some Major Event such as Alliances or Rebellions or more Players Eliminated or WG's Reign Ends),
That's when Oda will bring back Kaidou/Big Mom as their Appearance won't change anything in the World, They will only look like couple Fighters joining the War.
This Story made us always expect Villains to Return, it's that simple,
Very few Villains didn't appear after their Arcs,
Big Mom & Kaidou's Roles as Faction Representatives Ended in Wano Arc,
Oda can't bring them back now, cuz The World wd once again treat them as Major Players,
They will return when They no longer are considered a Threat on their Own,
When World Balance doesn't Exist anymore (Some Major Event such as Alliances or Rebellions or more Players Eliminated or WG's Reign Ends),
That's when Oda will bring back Kaidou/Big Mom as their Appearance won't change anything in the World, They will only look like couple Fighters joining the War.