A big reason why Big Mom is down is because of a rule of 3 situation happening here. 3 times we have had a chapter end in the same way but with stronger results each time. Law hits Big Mom with a very painful attack, which opens the door for Kid to hit her with a lot of force.
First time Law hits her with Shock Willie he is doing it with his sword at a regular length. Kid follows up by using assign and hitting her with basic steel bars. Result is that BM uses a year of her life to power up.
Second time Law hits her with a bigger shock willie by revealing he can stretch his sword, BM was begging Law not to use the move ("No, not that!"). Kid follows up with an intricate Bull Mech that hits her hard. Result is that she has to mend her broken bones and pulls out more advanced moves that we've never seen before.
Third time Law hits her with his biggest attack yet. The sword is extending to the ground and BM is desperately attacking Law to stop him by punching him over and over again. Law hits her with a stronger version of shock willie that puts a giant crater in the ground (compare the mountains next to it and how big it looks from Momo's POV). Kid follows up with a technologically advanced laser cannon attack. The big difference this time is that we can see Big Mom's face in reaction to Kid's attack. Result is that Big Mom is defeated.
This is the best place to stop the fight as there really isn't a way to improve on what we've already seen here, it will just be stalling or recycled content if it does. It wouldn't make sense to keep it going when we just saw the climax.
For another example of what I'm talking about look up the film "Kramer vs Kramer" and find the breakfast scenes at the beginning, middle, and end.
It's late where I'm at so I'm going to bed after posting this. But what happens during those breakfast scenes is what is happening here; the foundation of the events are similar, but there's a story and progression being told.
Add in the fact that we've already seen multiple fights end this way in the arc and you're only setting yourself up for disappointment if you think she's going to continue fighting after this.