Now that the battlefield has been brought to the surface. Muzan can easily make an escape the moment he realizes the sun may come up, much like how the train arc ended. I honestly don't know how this will end. Will he get away, or will this actually be the final arc? As of right now, I have a very hard time determining how the demon hunters will stall Muzan until sunrise. We have Water, Earth, Wind, Flower, and Snake pillar, with Tanjirou's rapid growth rate + Dance of the Fire God. Zenitsu, Inosuke, and Kanao, while beaten, could also act as the lynch pin to defeating Muzan such as with Upper moon 1.
On the other hand, if the author is pressured into continuing the series, I could also see this extending into a heroes lose into time skip sort of situation. Which is... less preferable for story's sake.
My money is on this being the final arc, though I really wonder how they're gonna win.