What is the significance of chapter 9, book 3 in Hard Times?

The last chapter of Hard Times, called “Final,” both ties up some loose ends of the plot and gives a glimpse into the future lives of some (but not all) characters. While virtue may be rewarded and malice penalized, settling moral accounts does not seem Dickens’s purpose. Rather than simply narrate these developments, the author intersperses numerous questions encouraging the reader to inquire into the characters’ minds and lives.
As could be predicted, the unpleasant Mrs. Sparsit will continue to live an inharmonious life. Mr. Bounderby undergoes no significant character transformation, and we see how his life will end. Mr. Gradgrind descends in the political universe as his philosophy, however amended, goes out of fashion. Tom, however, repents his actions and tries to reach his sister, but dies before doing so. It seems that Rachael will just keep on with the factory’s daily grind.
Asking about how Louisa sees her future, the author also conjures up the visions of the different characters’ outcomes.

Herself again a wife—a mother—lovingly watchful of her children, ever careful that they should have a childhood of the mind no less than a childhood of the body…? Did Louisa see this? Such a thing was never to be.

As he hints at here, he contrast between Sissy and Louisa is perhaps most striking, as Sissy does becomes a wife and mother; Louisa, instead, devotes herself to good works.
https://www.gutenberg.org/files/786/786-h/786-h.htm