Rob McElhenney, Glenn Howerton and Charlie Day Have Had the Final Episode of ‘It’s Always Sunny in Philadelphia’ Planned for the Last 10 Years

Dennis are in agreement on how It’s Always Sunny in Philadelphia will end, which is probably a bad sign for everyone else.
Sixteen seasons into Mythic Quest and, most recently, creating a multifaceted TV, film and sports entertainment company called More Better Industries, which he launched earlier this week.
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While speaking to Charlie Day on a plan for how the series should end over a decade ago, only to find that his collaborators already had the exact same idea. That settles it — they’re going to go back to selling gas door-to-door.
“Ten years ago, I came in and said, ‘Hey guys, I think I have an idea if we ever wanted to end it,’ and I started pitching it,” McElhenney told Adweek. “And Charlie said, ‘That’s exactly what I was thinking,’ and then Glenn just finished it. And we had realized that we had never talked about it, and all three of us had the same exact idea. We thought that’s probably a pretty good sign.”
Fans have long speculated that the show about the worst people in Philadelphia should end with every member of “The Gang” dying together in a catastrophe of their own doing — the Season 11 finale “The Gang Goes to Hell: Part Two,” in which The Gang (and Danny DeVito in real life) narrowly escaped a drowning death after being imprisoned in the brig of a sinking ship, has been speculated by some to be a sort of dry-run for the eventual ending of the series itself.
If McElhenney, Howerton and Day all had the same idea for how to close out It's Always Sunny, it does seem likely that they all agree that their characters can only be retired by putting them six feet under — for real, this time. We’ll be able to hear them crawling around in the vents if it’s another fakeout.