Perhaps there's another term for this, but I know it as "Trading on Promises." For example: a movie trailer itself is rarely "awesome", but it trades on the promise that the actual movie will be "awesome"- therefore the trailer is "awesome." If that promise is "broken" by the actual movie (by being non-awesome) then the trailer also assumes a non-awesome state.
Star Wars Episode IV: A New Hope is a trailer for the rest of the SW Universe. That is, it trades on promises that aren't fullfilled by the movie itself, but rather are hinted at in an awesome way. Those promises are either fulfilled by your imagination- or by the subsequent sequels.
Let me give some examples:
Luke is never a Jedi. He holds a lit lightsabre in all of 2 scenes. In the first one, he waves it around like a feather duster... in the second one he waves it around like a feather duster while a robotic-softball shoots mini-lasers at him. Based on the footage in the movie, Kenner had no right selling toys of Luke holding a lightsabre. Yet they did. By the truckload. And, arguably, it was one of the best toys for a young Star Wars fan to own- not so he/she could recreate the scenes in the movie, but so he/she could execute scenes from his/her imagination that fulfill the promises made in the movie.
That's really the best example, so I probably shouldn't have led in with it... but here are some more:
Obi-Wan's death & Father Skywalker's Death aren't avenged
Similarly: Vader isn't defeated
The Empire isn't overthrown
Leia doesn't choose between Luke/Han
Neo doesn't free the people/destroy the Matrix*
*Obviously, this is a reference to another movie, but you can't disagree that this does not happen in A New Hope.
The key, though, is that A New Hope feels over when it's over. Not like (IMHO of course) Fellowship of the Ring which ran for 3 hours and then called a timeout while they finished making the rest of the movie(s). So, the contract with the audience isn't broken... somehow we understand the promises WILL BE fulfilled, even if we don't get to see it. OF COURSE Luke will go on to finish training to become a Jedi. OF COURSE the Empire will eventually be overthrown. OF COURSE Vader will get his comeupance. Somehow we're okay with this not actually being in that first movie, and I think people would have been okay with it had those events never been realized on film, but simply remained as assumptions. (Anchorhead, would love for you to chime in here.)
Speaking of the Matrix, when I saw that movie in 1999, I immediately went home and described the movie scene for scene for my younger brother. When I got to: "He drops the phone and flys away from the city and then some screamo-rock song starts." He was shocked! How could they leave the story there WITHOUT LETTING NEO SAVE ALL OF THE PEOPLE??? What was the point of the movie, HAVE HIM SAVE MORPHEUS? His shock shocked me. I didn't have ANY of those thoughts after seeing the movie. But the way I retold it, he expected that promise to be fulfilled in the movie itself... and not left to my assumptions or to future sequels.
Okay, that's all for now.
IT'S MY TRILOGY, AND I WANT IT NOW!
"[George Lucas] rebooted the franchise in 1997 without telling anyone." -skyjedi2005
"Yeah, well, George says a lot of things..." a young 1997 xhonzi on RASSM
"They're my movies." -George Lucas. 19 people won oscars for their work on Star Wars (1977) and George Lucas wasn't one of them.
Rewrite the Prequels!