there's no way Kid and Law are losing
In One piece, almost every time a fight is supposed to end in failure, its a stomp. Like look at Luffy vs Kaido(in act 1) or Kaido vs scabbards. Kid and Law vs Big Mom are nothing like those fights as even with her lifespan power up, she is still unable to beat Kid and Law. And it has been many chapters since they have been fighting.
If a fight is long and drawn out, and the villain needs to lose for Luffy to ultimately be successful(as in the case with big mom where Kid and Law's failure means the alliance's failure), the villain will lose.