Now that Harry Shearer has agreed to return to The Simpsons, we will never know whether showrunner Al Jean’s earlier statement that the show would recast all of Shearer’s parts was an empty threat. It would be a tall order to replace characters as diverse and as central to the series as Ned Flanders, Mr. Burns, Waylon Smithers, Principal Skinner, and Reverend Lovejoy, not to mention God, The Devil, and Hitler.

But I’m inclined to believe that Jean really meant it. During tense contract negotiations in 1998, Fox executives went as far as hiring casting directors in five states to replace its disgruntled stars. And as hard as it is to imagine someone new voicing Dr. Hibbert, let alone Bart Simpson, this latest round of negotiations may have proven a proposition that has vexed and delighted the show’s die-hard fans in equal measure — The Simpsons may never end.

Those uber-nerds (myself included) have often debated what would finally be the death knell of the series. Bill Oakley and Josh Weinstein, show runners for seasons 7 and 8, went on record as having expected the show to wind down shortly after their run, which made them more comfortable bringing an experimental bent to the episodes produced under their tenure.

It’s not a crazy thought. Most series, even those that become television’s biggest hits, are lucky to last for ten seasons. It was natural for Oakley and Weinstein to suspect that the end was nigh.

Instead, the show has chugged on to the present day, and any hope that The Simpsons would bow out gracefully has long since been discarded. Shearer’s acquiescence ensures that the original voice cast is signed for two more seasons, with a network option for two more, taking the show through Season 30.

The current episode order would put the series within spitting distance of Gunsmoke’s record for most episodes, a milestone that Jean has mentioned in the past. But even that accomplishment seems unlikely to convince the team behind The Simpsons, who have established such a cozy infrastructure, to cease churning out episode after episode at this petty pace. With the series’s glory years long behind it, the show has settled into a comfortable groove and has been producing seasons of roughly equal, if diminished quality, for years now.

Once upon a time it made sense for fans and critics alike to ask, “What more is there for the show to say? What stories are left to tell? How long can this go on until the series is simply creatively exhausted?” With those questions looming, the idea of The Simpsons reaching its end point once seemed like a foregone conclusion among the show’s most devoted followers, with the assumption that it would happen sometime in the near future. But by the end of the current order, those questions will have been asked for twenty years, and they do not seem to have given the show’s producers any pause. At this point, it’s safe to say that the series ending for creative reasons is unlikely at best.

So what are the chances that, as Troy McClure once suggested, the show ends because it becomes unprofitable? It’s not outside of the realm of possibility. The landscape of television has changed dramatically in recent years, and the traditional players are still scrambling to figure out how to adjust their business models in the wake of those changes. In the contentious 2011 contract negotiations with The Simpsons’s cast, Fox executives convinced the voice actors to take a massive pay cut amid threats that the show would otherwise be canceled due to its high production costs. Nevertheless, an agreement was reached; the show was renewed yet again; and it has continued to air with no public complaint from Fox.

But even if the series itself were legitimately unprofitable, many have theorized that the actual television show may serve as a loss leader for Fox. Every new episode of The Simpsons, and each new gimmicky contest or mystery or crossover with another series that comes with it, keeps the show in the public consciousness. Each episode serves as a thirty-minute advertisement for the branded freemium game, and the new Krustyland area at Universal Studios, the collection of official guides and spin off books, and the boatloads of Simpsons merchandise that Fox cranks out every year.

It all also adds grist to the mill of the blockbuster FXX deal that finally brought the show’s reruns to cable television. Sure, someday, production costs could theoretically balloon to the point that it no longer becomes worthwhile to produce new episodes, but the series is a reliable machine now, with a recognizable brand name in an ever-growing sea of indiscriminate entertainment options, and it seems doubtful that Fox or the people behind the show will give that up anytime soon.

That leaves only one way that the show might end, and it’s one that fans of The Simpsons have ruefully contemplated for years: one of the major cast members leaving, or worse, dying.

The Simpsons has dealt with this issue at the margins before. Doris Grau’s death in 1995 prompted the show to retire her lone character, Lunchlady Doris. (Although recently, the show bafflingly brought the character back as “Lunchlady Dora”.) After the inimitable Phil Hartman’s 1998 murder, Lionel Hutz and Troy McClure were quietly relegated to crowd scenes. When the The Simpsons’s producers balked at Maggie Roswell’s contract demands in 1999, the show killed off her most notable character, Maude Flanders, and recast others like Helen Lovejoy. And recently when Marcia Wallace, the voice of Edna Krabappel, died, the show sweetly acknowledged her passing and depicted the other characters mourning Mrs. Krabappel. In each instance, The Simpsons kept rolling along.

But Harry Shearer’s alleged departure was the first real test of whether the show would be able continue without one of its six principal stars, the ones who voice the show’s main characters and the most recognizable denizens of Springfield. While I would never want to downplay the incredible contributions of Grau, Hartman, Roswell (who later returned to the show), or Wallace, their characters were compartmentalizable enough that, while a bit awkward at times, the show could continue in their absence without a fundamental change.

Shearer leaving, however, would be the first time the show had to seriously confront this issue. Mr. Burns could not simply be shuffled to the background. Principal Skinner could not meet an untimely demise with the repercussions largely confined to a single episode. Ned Flanders could not be retired without fanfare only to be brought back years later with a slightly different name. At the very least, the show would be unable to sweep all of Shearer’s characters under the rug in this fashion. Maybe, the fans speculated, this would be the straw that broke the camel’s back in terms of the show’s longevity.

But it wasn’t. We’ll never know for sure if Shearer would really have left, or if the show really would have recast his dozens of characters, but I think The Simpsons would have made good on Al Jean’s promise to continue on without him. There’s too much at stake, too many millions of dollars in play, too many people’s livelihoods in the balance, and too much institutional inertia to stop the series now. If Shearer leaving wouldn’t do it, then there’s little standing in the way of the show continuing in perpetuity.

Some of the die-hards try to create a distinction between Shearer’s role in the series and those of the actors who provide the voices for The Simpsons themselves. They assume that if Dan Castellaneta left, having to find a new Homer Simpson might be too much for even a Fox executive to stomach. But I don’t believe it. We’ve had a new Kermit the Frog, a new Bugs Bunny, and countless other new voices for a host of iconic characters. If the show was willing to recast the Burnses and Flanders and Lovejoys of the world, there’s no reason to think they’d draw the line at The Simpsons.

There is, however, one unexplored possibility in this vein. Negotiations with all of the principal cast members could break down at some point and theoretically end the series. With all six of the main stars holding out for higher pay, Fox claimed that it would recast the entire show, first in 1998 and then again in 2004. The studio reportedly ran into difficulties finding actors who could replicate the multitude of voices necessary for the show’s hundreds of characters, but when push came to shove, the two sides cut a deal. The network appeared fairly serious about cancelling the show in 2011 if the six principals refused to take a pay cut, but as in prior standoffs, both the studio and the actors eventually backed down and worked out a compromise.

Fox makes too much money from The Simpsons as a cultural institution to simply let it fade away. And while I would never want to diminish the way in which Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria, and Harry Shearer have proven to be the lifeblood of the series in their brilliant performances, the flexibility of voice acting means that cast members like Shearer can, in fact, have the freedom to pursue other projects while still meeting their commitments to the show. By the same token, the substantial sums involved make it doubtful that all six would walk away from that kind of arrangement, no matter how sour the notoriously prickly Shearer seemed about it.

On the whole, a collective cast walk out seems unlikely. The studio and the show’s producers have shown a willingness to replace individual voice actors if the issue arises. The studio has cycled through generation after generation of writers, animators, and the other employees who keep the show’s trains running on time, all without threatening The Simpsons’s survival. The show’s financial value to Fox as a going concern does not seem to be in real doubt, and after 26 seasons, including many in the shadow of persistent complaints of decline, the end of the show coming as a creative decision seems a distant possibility.

So here we are, staring down the barrel of another two years of Simpsons episodes, with the substantial likelihood of two more on the horizon after that, and no end in sight. I still enjoy the show for what it is, and as someone who’s been watching as long as I can remember, the thought of The Simpsons finally ending is a melancholy one. But so too is the idea that the series will truly turn into the zombie its critics accuse it of having become, forever stumbling forward, impervious to death.

The idea of The Simpsons becoming a Ship of Theseus, of having so many parts gradually replaced until nothing remains of the show I fell in love with, not even the talented actors who brought the beloved oddballs of Springfield to life, is a disquieting one. But if all these blows haven’t felled the show, it’s hard to imagine what would or could. They may genuinely never stop The Simpsons.