Luffy didn't beat her ass and he will propably never do this in the future.
People also don't realize that Luffy leaves certain actions and tasks to his allies. Leaving Ace's fruit to Sabo was one of those things (since he quit the tournament the last round)
People also don't realize that by defeating Katakuri, stealing her Road Poneglyph, taking Sanji back, ruining her castle and party, he effectively beat her crew without having beating her. This is exactly what Morgans is saying in the newspaper and why he's considered a 5th Emperor.
Big Mom here and now is Oda tying up loose ends and giving her the conclusion she deserves as an enemy. IF (and I seriously mean if) she is in Elbaf, there is zero chance she will be the main villain. There is nothing truly interesting left to tell about BM, outside of her clear Rocks flashback which is also shared by Kaido (so it'll probably happen this arc), and someone revealing to her she ate Caramel and her friends.
That's quite literally it. The whole thing about Loki hating her comes from the fact that Lola denied the marriage, so it drove her to hate Chiffon, a plotline already done because Chiffon escaped and was reunited with Lola and her father. Bege's cover story literally ties up everything you need to know about Big Mom.
The ONLY thing that really is unaddressed is Smoothie and the rest of her crew. That's it.