Song of Solomon by Toni Morrison. Guitar and Milkman, the two main characters, are put in a fatal collision course, but the author leaves it ambiguous who lives and who dies. According to Wikipedia, Milkman dives towards Guitar and dies in the process; when I read it in 1979, it wasn’t so clear cut, and either way, Guitar’s fate remains unknown. Few white readers ever sympathized with Guitar; Black readers of that day, I’m not so sure.
Anyone who has ever read The Neverending Story will recognize the phrase, “But that is another story that will be told another time.”
There was a series on a while back that never answered the riddle, “what did one snowman say to the other snowman?” That’s all I can think of, though.
Koxinga, that was Lost, and the answer was given - “Smells like carrots.”
What’s Eating Gilbert Grape?. The book ended with the fire; the movie did tack on a real ending.
Ah! An answer! I knew my faith in that series wasn’t misplaced.
“What do you get when you multiply six by nine?” is not the question. We know this because the computer that was supposed to find the Question and encode it in Arthur’s brain, aka Earth, became contaminated by the arrival of the alien ship full of “middle-man” workers. Managers, hairdressers, telephone sanitizers, et cetera. Arthur was descended from those people, not the carefully computed constructs of Earth.
I had heard that Larsson had unfinished work behind, but I wasn’t sure if the unfinished work included Lisbeth’s twin sister. I hope that what he left behind was fleshed out enough that it could be published some day!