I'm still convinced that the relation that was created between Linlin and Tama during the former's amnesia will have its importance later. Especially since the CP0, the people who may reveal her who Mother Carmel truly was will certainely return to Wano.
Maybe if Big Mom goes through another mental shock due to her having gotten the big reveal, if that happens of course, she'll somehow remember Tama as the last genuine friend she had and than that alongside Tama being harmed will causes her to snap out of her mental state with her having reverted back to her original personnality again.