I feel slightly the same.
I think she will show up, and she will essentially be Luffy's benchmark before they move onto whatever villain/narrative piece they have next on Elbaf.
Big mom is the prototypical bully, she mostly gets by on aura & intimidation. Yes,she is a freak of strength & Defense but der d.f even leans into her aura of fear. Luffy can now bypass her defenses and he was never afraid of her, so I see Luffy destroying her physically & mentally, breaking her will as he is want to do.