I was thinking of two long-running media franchises today. First, because last night was the 26th season premiere, The Simpsons. Second, because I was listening to the very awesome Rachel and Miles X-Plain the X-Men podcast this afternoon, the X-Men comics (and all their attendant media incarnations). While they are different in most respects, they have certain key elements in common; both have large (if steadily dwindling) fanbases; both take place in vast multiverses filled with dozens, if not hundreds, of supporting characters; and both went through "golden" eras very early in their runs, which attracted a tremendous audience of loyal followers, many of whom now feel that the respective franchises have all but exhausted their potential and need to be, if not retired, then downsized considerably in the interest of preserving what was great about them in the beginning.
Which, needless to say, is not going to happen anytime soon. In both cases, there's still a critical mass of both younger fans — who may not be aware of or even like the "classic" stuff — and older fans, who still tune in out of nostalgia and the hope that things might get better over time. That optimism, and a constant flow of reissues and reimaginings of vintage material, is the engine of survival for just about any long-running franchise, be it a TV show, a movie franchise, a comic book series, or a line of video games. Even if you hate Star Trek Into Darkness, or the latest lame-ass Final Fantasy release, you still have the memories of the better entries to sustain your affection for those properties. Consequently, it's very rare that a popular franchise just disappears completely; the only recent major example I can think of is The X-Files. (But even that might be due for a renewal.)
So for fans, longevity is a double-edged blade. It's great that something you loved a long time ago is still around, attracting new devotees and going strong. But the agent of that durability might be something you hate, like the Star Wars prequels or the Transformers movies. At times like these, it's important to retain some perspective; lots of people thought the original Star Wars movies were silly when they came out, it's just that they probably weren't in your peer group. And those old Simpsons episodes may seem timeless and brilliant to you, but for someone born around the turn of the century, they're probably full of baffling, outdated references and corny jokes.
That said, there is a big danger associated with longevity, and it's not what you'd think. Often you hear about creators losing sight of what the franchise was supposed to be about and going off on a bunch of pointless tangents. But I don't think that's the real risk at all. The big concern is that the people who are in charge of the thing will turn it into what they thought it was supposed to be all along.
Consider The Simpsons. Today, we think of it as a subversive program that helped kill the saccharine '80s family sitcom (think Family Ties, Full House, and Cosby) and ushered in an era of sophisticated, deep, self-recursive humor. But that only describes a small part of the show's early triumph. What really made it work was that there was plenty of character development and worldbuilding. The characters felt real, with genuine struggles and doubts (Homer's alcoholism and weight problems, Bart's efforts to pass the fourth grade, Lisa's desire to fit in versus her need to find her own identity, Marge's boredom), and inhabited a universe that, while rooted in humor, felt fairly consistent from episode to episode. In a lot of ways, the show, rather than turning its back on convention, actually embraced many of the aspects of the humanistic sitcoms of the '70s and '80s, like Taxi and Cheers. But after about seven or eight years, the show reversed its priorities from characters and stories to pure humor. If a character's established personality or backstory got in the way of a joke or even a simple gag, the funny thing took precedence. Homer became a violent buffoon, long-running characters were killed off (like Maude Flanders) or revealed to be someone else entirely (Principal Skinner, aka Armin Tamzarian), and the town was destroyed or moved several times. Something similar happened with the later seasons of Futurama on Comedy Central. (Remember the hilarious Susan Boyle gag? If so, congratulations — you remember who Susan Boyle is!) The shows had started out as more than just cartoon comedies, but now they were simply that. As one Simpsons writer put it in the early '00s, "The humanity has leached out."
The X-Men presents a number of parallels. Under Chris Claremont in the '70s and '80s, Uncanny X-Men was superficially a superhero team comic book, but it featured complex, antiheroic characters with complicated relationships and conflicting personality traits, and dense plots that unfolded over several years. (It was also one of the first Marvel comics that really portrayed female characters as autonomous individuals, rather than love interests, airheads, or strident caricatures of "strong" women.) While Claremont was, for the most part, a fairly conventional comics writer, his stories and dialogue were fairly sophisticated for the era, and his goals were no less ambitious: Over time, if they survived (which was not always a guaranteed outcome), the mutants would grow older, wiser, and move on with their lives. In Claremont's original character arc for Cyclops, Scott Summers was supposed to stop grieving for Jean Grey, marry Madelyne Pryor, quit the team, and raise a family with his normal, human wife.
But at some point in the mid-'80s, Marvel decided that X-Men was a straight superhero franchise, and against Claremont's wishes, resurrected Jean, put Cyclops back in costume, reassembled the original team as X-Factor, and gradually transformed Madelyne from a sympathetic, three-dimensional heroine into an evil hellbitch in a skimpy dominatrix costume who had to die in order for Scott and Jean to be fully reunited. (Madelyne and Scott's infant son was reconceived by Rob Liefeld as a Schwarzeneggerian vigilante from a postapocalyptic future, with a cyborg arm and big guns.) As a result, X-Men, which had long been an unorthodox series defined by credible relationships and personalities, became another comic book about colorfully costumed people with improbable physiques and crazy powers beating each other up in public. Eventually, superstar artists like Liefeld and Jim Lee would force Claremont and other original writers like Louise Simonson off the X-books entirely, as the focus shifted from character-driven stories to violent, teeth-gritting spectacle, just as The Simpsons went from nuanced satire to "wacky" comedy.
In both cases, neither series suffered major setbacks; indeed, they endured and thrived. Since its late '90s critical nadir, The Simpsons has been renewed for sixteen seasons (more than twice the length of the original "classic" era) and spawned a hit movie. X-Men survived without Claremont's continued involvement (though he still pens a series from time to time) and has generated a dozen or so comic book spinoffs, as well as a popular cartoon series and a successful if wildly uneven film series. Both franchises now likely have more fans now than they probably did when they were "good," and there have been some decent episodes and story arcs since their respective golden ages. But at the same time, they've become more machinelike and predictable. The strangeness and idiosyncrasies that made them unique have been refined to the point where both register as formula-driven commodities, rather than pure stories. They exist to fulfill a readily-identifiable function, rather than being some cool, weird thing that doesn't remind you of anything else.
You don't have to have a master's degree in critical theory to recognize that this is going to happen to everything that becomes more than just a moderate success. It's happened to Star Wars, it's happened with Star Trek, and it's happened with the Middle Earth movies. It will almost certainly happen to Game of Thrones and the Marvel Cinematic Universe, ironclad as they seem at the moment. Any beloved franchise is just a few seasons or sequels away from becoming a dull affair, no matter how talented or devoted the people involved. This is why most third movies in a series are bloated trainwrecks, and why most TV shows stop being good after four seasons, and watchable after six. It's why long-running epics become interminable slogs after three books, and why comics become unreadable, entropic ordeals once the issue numbers hit triple digits. With a handful of major exceptions, like LotR (which was really just one big novel anyway) or Gaiman's Sandman, popularity and longevity ends up killing what made something special to begin with. But because we love those things so much, we keep hoping that a new vision or a new creator will find a way to make them special again. This is the honeytrap of genre, and most of us keep falling for it.