oda never reveals antagonists full arsenal like this if he wants the antagonist to be defeated later
oda didnt reveal queen or kings hybrid throughout wano, thats because he was saving it for the fights against zoro and sanji
just like you wouldnt see doflamingo use his awakening on someone else before fighting luffy
the gorosei are already fighting, its been a fair long now, way too long to be some kind of prequel fight, this is their actual fighting happening right here, its there arc
there is no point and no interest for them to come back, the strawhats already fought them, it would just be repetetive
it would be like if the beast pirates came back