Someday the nearly unthinkable will happen and “This Simpsons” will air its last episode.
What do you want to happen on the last episode? Another “future” episode, but of Homer’s death? Bart goes to juvie hall? Homer wakes up next to Suzanne Pleshette?
Bart turns 11. Lisa turns 9. Maggie walks.
Marge leaves Homer and hooks up with Ned Flanders and takes Maggie with her.
Bart joins the Springfield chapter of the Crips and gets killed in a drive-by.
Lisa finally comes out of the closet and moves in with Patty and Selma to explore her newfound feelings.
And as the closing credits role, Homer sits on the couch watching TV and drinking beer, oblivious to everything.
… and, as the camera pulls back away from the house, it passes by the Springfield city limits sign- and we finally find out what state they’re in.
I picture something like RevTim’s idea except that, when Homer wakes up, he and the whole family are back on the Tracey Ullman show in the original animation style with Tracey coming out onstage telling everyone to go home.
cameo by me!!! But the show will never really end, the last episode will be frame by frame remake of the first one, just with updated animation.
My ideas:
Pam wakes up and Patrick Duffy walks out of the shower and Donna Reed is nowhere to be found
The family is sentenced to two years of jail time, which will end up being forever since they never age
Everyone dies in a fiery explosion, perhaps caused by Ralph, a matchbook, and a gas leak near the Springfield Tire Fire
Homer heads to Seattle to pursue a radio career and Moe closes the bar one last time with a longing look at days past
Milhouse leaves town to follow Lisa after her election to the US House, Homer passes up a chance to tour with Mel Torme to remain in Springfield
Everyone in the Springfield Shopper newsroom shares a group hug
Bart departs from a helicopter on the lawn barely escaping a selective service notice
A triple-wedding of some sort
They explain:
1)Where Springfield is
2)What the dreaded “Rear Admiral” is
Other than that…I pretty fine with whatever
well…maybe letting Sideshow Bob finally kill Bart
Maggie says “That’s all, folks.”
The show is abruptly cancelled in mid-season, with no “last” episode. Then five years later a Simpsons TV movie special is aired, which shows us what happened to the characters.
OR all the voice actors for the major characters walk, and the show has to be renamed and rebuilt around three minor walk-on characters and Homer’s cousin Bill who’s just moved to town.
“The Springfield Arms” starring Comic Book Guy.
I expect something sort of like Lumpy’s idea, except that instead of the real life voice talent walking, the show is about the bug-eyed, yellow-skinned “actors” who play Homer, Bart, etc. deciding to quit. Some form of hilarious hijinx ensue, with a maudlin freeze-frame at the end while the credits run.
Homer’s ineptitude finaly does it – complete nuclear meltdown at the Springfield Nuclear Power Plant, & total obliteration for the town.
They’ll hire Chris Carter to write the last few episodes, leading to a finale that’s as understandable as James Joyce, and us uplifting as John Milton.
I’m feeling cranky, can you tell? 
Ranchoth
(Magnatite caves my ass…)
Tony gets whacked. Carmella marries that wallpaper guy and takes over the family business. Meadow gets back together with that mulatto guy, and he knocks her up. A.J. gets arrested for pulling a knife on some guy in Central Park (oh wait, that already happened!) Dr. Melfi quits her practice, reunites with her husband and kid, and they go on a “Partridge Family” style tour across the country.
Oh wait. I thought this thread said what should happen on the last SOPRANOS episode, not SIMPSONS. Never mind. Carry on. 
Three Words: Maggie’s Killing Spree.
The thing is…they’ve done all the big things that should happen on a last episode.
Remember the “Simpsons Bible Stories”? They all walk out and the Day of Reckoning is upon us. The Simpsons are condemned to Hell (with the exception of Lisa- but why the hell did Marge have to stay behind?), while the Flanders ascend to Heaven. That would have been great for the last episode ever. A downer but a funny one. Someone on the snpp page mentioned that.
And remember when Mr. Smithers FINALLY kissed Burns? That was in “Lisa the Skeptic” and it totally made the leap from innunedo (the staple of this running gag) to actually showing emotion. There was no way Waylon could talk his way past that (though his computer sign on graphic was pretty suggestive too! ), so I personally think they should have saved it.
Same with “Behind the Laughter.” Not that it wasn’t good, but they’ve done everything. They’ve shown us what happens to the Simpsons in the future (in two episodes), so I don’t know what other earth shattering thing they can do to shock us. And when they do make the last episode ever, you just know people online are going to be bitching about it from here till kingdom come.
That said…I don’t want to think about it. But if I had to choose something to happen (other than a long boring clip show), how about an actual alien abduction, by Kang and Kodos? At long last, it is revealed that the aliens live among us. I just think they should be included.
Something un-canonical.
Although James Earl Jones has returned a few times, we haven’t seen ‘Sarek the Preparer’ since Season Two’s ‘Treehouse of Horror’.
It should include…
Every…
Single…
Character…
That ever existed. Living or dead.
And I like the idea about it being finally revealed what state Springfield is in. Except it should be revealed that they’re Canadian, and they just thought that they were from America. Or that they’re in Jamaica. Or something equally silly and unexpected.
They should have…
Every…
Single…
Major character…
Get killed. Somehow.