But isn't that pretty much what Fellowship of the Ring, An Unexpected Journey, Harry Potter and the Deathly Hollows Part 1, and probably Mockingjay Part 1 are?
A lot of TV shows do the same thing with a cliffhanger episode as the last episode of the season to get us to tune back in the next season.
The Destiny trilogy was like that. I don't think they are complete on their own. But together, all three make a complete story.