|I'm sure he'll be fine.|
The issue goes back to story structure. Regardless of whether one uses a three act structure, a five act structure or the 22 plot points of the Hero's Journey, a resolution is always the last step. It's not always in the heroes' favour but it is an ending, one way or another.
There are points where I feel that cliffhangers are acceptable. Some stories are too big to be told within typical page or time limits. Dividing them into several parts is a valid choice but it's a challenge to make sure that the audience is satisfied at the end of each installment. And it's critical that the audience knows that the story is ongoing.
I am not a fan of the start-on-a-cliffhanger technique, where the audience is shown the heroes in peril or doing something uncharacteristic, and then we flash back to "Two days earlier" and the creator shows how they got to that point. It invariably feels like a cheap tactic to generate tension. It's not even a particularly effective tactic since it's been used so many times.
If an audience thinks the creator is stringing them along in order extort more sales, they will be rightfully furious. It's a fine line between a hook and a cliffhanger, and it's mostly in the audience's perception.