Big mom has some VERY cool powers, had a great flashback and her life in general is interesting, Totland is one of the coolest locations in all of one piece and her crew has some cool dynamic and design
. But she absolutely SUCKS as a main villain, absolute garbage even during WCI, so even if she returns I hope its just as a side thing or a brief clash, and not as THE villain of an arc, and that her focus now is hunting down Law and Kid rather than Luffy