People remember the initial lines of novels (e.g. "It's a truth universally to be acknowledged..."). And they remember the final lines of short stories (e.g. "He was absolutely sure Helen wouldn't have wanted him to be so alone"). But they do not remember the final lines of novels.
Go ahead, Name exception after exception (I can think of one, the final line to A Farewell to Arms, though I mostly only remember it because it's infuriating). But I will stand by this opinion until my dying day. The final line of a novel is not nearly as important as most of the other lines in it, because by the time the reader's gotten to the final line, they're probably mostly skimming anyway.
There's a reason for this! Short stories are precise. They end on a needlepoint. And the ending is supposed to keep ringing in your head for a few minutes afterward.
Novels are not like this. They begin to end even before the ending has come. People don't want a novel that rings on for a few minutes afterward. They want a novel that has real, living, vibrant characters. And when you've spent ten hours reading about some real, living vibrant characters, you end up wanting to know what happens to them after the end of the story. That's why many novels have one or more denouement chapters that serve to wrap up most of the loose ends. These chapters are fun! They're heartwarming (even when they're tragic), and they serve to cement the story in the reader's memory. But they're not high-intensity. Indeed, if they were high-intensity, it would defeat the purpose, because then they'd be introducing new threads, new thoughts, and new possibilities.
Because of this, the reader tends to end a novel at a lower level of emotional arousal than they end a short story. And because of that, there's not nearly as much interest in the final line.
In fact, I actually cannot remember the final line of my book. And I refuse to look it up, because it's not important.