The final fight that is starting right now has been built up ever since the beginning of the manga, so yes, I believe that the manga will end after it.
Of course. After Ushio, the protagonist, beats his main rival Kuze, the manga will have reached its climax. It would be unnatural to prolong it after that.
Sesuji wo Pin! is a bit of a different case. Its rankings sunk during the middle of the final tournament and recovered only a little too late, so that definitely played a role in its ending. But at the same time, the author managed to show what he wanted to draw, and managed to finish with an ending much more natural than the majority of the magazine.