I love these kind of endings and I'll tell you why: A big part of it is the writer, treating me, the reader as an equal and not spelling everything out, instead trusting me to draw the correct conclusions from his/her writing. My imagination gets engaged. I get challenged to look for my own ending, play it out for myself. It immerses me even more in the story, because I get to play a part in it. And then there's the angle that I as the reader feel the writer is confident and skilled enough to not lead me down a wrong path. I am a sucker for competence. This self confidence and skill feels to me not unlike the Piper of Hameln, leading the rat(s) on
The OP asked for examples of open-ended works, but the only one I saw offered was Star Wars. The first 3 Tarzan novels and the first 3 John Carter novels, both series by Edgar RIce Burroughs, were open-ended until the 3rd novel. They were not what I would call cliff-hangers - each novel's primary conflict was wrapped up. But in the first 2 of each, something happened to separate Tarzan/Jane and John Carter/Dejah Thoris.
I think with an open ending the reader uses context clues to determine what happens, whereas a cliffhanger is designed to prepare you for the next episode or book in a series. I think, but I'm not certain.
