We have no idea if the top was going to fall, and that is exactly what Nolan wanted- he wanted to instill doubt in the minds of the moviegoers, and was successful at achieving that.
The top is going to fall. It starts to wobble (precess) and in a few boring minutes it will finally topple. If Nolan doesn't know that, he's an idiot. Expecting us not to know this shows his contempt for us.
Neither DiCaprio nor Murphy are looking for emotional catharsis. DiCaprio supposedly has one in his confrontation with the false Mal but the movie is so badly written even the fans have trouble realizing this. What DiCaprio wants is to get his kids back and the catharsis comes, supposedly, in rejecting the temptations of the false Mal. Any catharsis DiCaprio has is a means to the end, which is earning Watanabe's intervention. I'm not sure in what sense the character's motives could be subjective.
The notion that emotional catharsis will move him past caring whether he really gets them back is obviously absurd.
Cillian Murphy's catharsis is based on falsehood. The question of whether it's still worthwhile has some interest perhaps but the movie doesn't dramatize it. If such issues were what the movie was about, we might have seen the camera follow DiCaprio past the spinning top, then close in on his face, eyes shut, as he embraces the children. Is he dreaming? Or we might see Cillian Murphy confronting Tom Berenger.