And yet there are plenty of TV series that have lasted for 10 seasons, 15 seasons, even 20 or more seasons rehashing the same formula, yet still retaining fiercely loyal audiences.
Fiercely loyal but shrinking audiences, that would shrink even more quickly if they had to wait 2-3 years and pay 10-20 bucks for every installment.
Congratulations....you just gave an excuse for someone to create "a more impressive version" of Citizen Kane, the Sistine Chapel, and the works of Shakespeare.
Who am I to say that no one ever will? People have tried, long before I was born. They haven't succeeded yet... as far as I know - though they have done a great job maintaining and preserving those works of art, haven't they? I wonder if they would make the necessary improvements to those works if they felt that they were perfect as they were.
Ever hear of the law of diminishing returns.....? You keep stopping and restarting a franchise, and covering the same old origin story in reboot after reboot, and whatever power and emotion the story originally held will be watered down and forgotten forevermore.
Yet every reboot tells the origin story differently, so it's not the same old, and by the third retelling, only 'old people' remember the first version, so it's not watered down for the target audience. Again, a new generation tells its own stories, that's how these characters can go on forever, not by new generations telling the previous generations' stories.
Since when did Star Wars "go out on a high note" --- or go out, period? Last time I checked (30 seconds ago), Star Wars is still churning out umpteen video games, novels, comic books, cartoons, live action TV series, and most likely feature films for generations to come. Remember that Lucas still has a whole 'nuther post-Episode VI trilogy to get to. Too bad Star Wars "died naturally," and that "no one cares" about it anymore....somebody needs to inform Lucas and his media empire about that
We're talking about films, so unless you have information about a new Star Wars film being made (you don't) then that must be what I was referring to.
If I chose to switch subjects, then none of these series have ended or rebooted, there is always multimedia for the hardcore fan. Again, you rely on non-film examples to inform your film strategy instead of film history. If Star Wars hadn't had the presence of mind to end their stories, to go out on high notes in their trilogies, there wouldn't be any of the things you mentioned. Without an end to Luke's saga in the films... how could anyone possibly write the Thrawn Trilogy? If not for a definite arc for Anakin Skywalker, how could you do Clone Wars with any assurance that you wouldn't conflict with Anakin's unfinished story? Definite and final endings are what allow other media to tell stories that feed into it, all in the same continuity! Star Wars is proof of that. It's also proof that those things are for hardcore fans, not the masses.
But you don't want that for Avengers, you want one long endless continuity, which is a nice dream, but every attempt at doing so has ended in stagnation, decay and rebooting. Bond holds an impressive record, but modern and superheroic attempts at such infinity have been far more brief.