The cliffhanger in The Giver is its ambiguous ending. Lowry never lets us know if Jonas and Gabriel live or die, he leaves it up to reader to make the choice. Lowry, however, tends to write more optimistic stories and he does give us hope for our hero when he writes,
"Behind him across vast distances of space and time, from the place he had left, he thought he heard music too. But perhaps it was only an echo," (p 180).
We get the feeling from these final two statements in the book that he might have a chance at survival, but again, we never know for certain. Perhaps Lowry left the ending ambiguous to show us what types of people we really are. Are we optimistic or pessimistic? Do we want our hero to make it? Either way it sounds as if Jonas is at peace. If he dies, he is hearing music as he embarks on that journey, and if he lives it sounds like a lovely place to stay with its music and colorful lights.
Well, "cliffhanger" sort of overstates things (I wouldn't use the term), but the main thing left in suspense at the end of The Giver is what happens to Jonas. He's left the community he knew (with baby Gabe), and at the end of the novel, he's slid down a snow covered hill. We don't know if he's going to live or die as a direct result of the sledding, and we don't know what's going to happen to him in a larger sense if he lives. Well, hmm. Maybe that is a cliffhanger at that.