Kidd: "We must use our ace up our sleeve !!"
Kid and Law have gone all out and managed to take down BM and bury her essentially. She'll be fine but that doesn't mean she gets up instantly. And if she does then it means Law and Kidd are going to lose as they don't have much left in the tank. Either way the fight is pretty much close to being over.
She's not winning. Narratively, this would then make zero sense. This is the same illogical BS I argued for months with people who denied Zoro could have more significance with King after he used his "strongest" move on the roof.
Nothing suggests the fight won't continue to be drawn out. Nothing suggests they won't get hurt more. Nothing suggests Kid can't unlock AdCoC. Hell, Kid HAS Conquerors and we know he hasn't used it yet. Virtually nothing suggests anyone is going down next chapter either.
She's poised to be defeated by Law/Kid, and she's higher on the heirarchy than King/Queen where defeating a Yonko this second would not be appropriate for the themes in the story.
You can rag on me all you want AFTER you know what 1031 is though, not before. Just be prepared for the opposing mentality