8 Ways It's Always Sunny In Philadelphia Could End
7. They're All Figments Of Frank's Imagination
It's safe to assume that Always Sunny's ending could flip the show on its head, as that would be very typical for the writers. While this idea does sound crazy, there are already fan theories fluctuating amongst the fandom that feed into it.
In this ending, there would come a reveal that Frank is a lonely and unstable man who imagines all of his friends, possibly even personifying pet animals that he has around the bar. You may say, then what about season one where Frank wasn't there? The answer to that is simple; season one was a backstory Frank made before arriving - which explains why it was so different to the new seasons.
Regarding each characters real-life counterpart, the fan theories also step in. Dennis could very easily be a cat, as he's arrogant, prone to fits of rage/scratching and even married a feline fanatic (Maureen).
Charlie would undoubtedly be a rat, as the show is constantly comparing him to those little ones. There's no argument that Mac isn't a dog in human form, as he's loyal to a fault and always acts as a bodyguard - despite being terrible at it. Then, there's Dee, and well, "Dee's a bird".
This would be a genuinely ridiculous ending, but ridiculous is Always Sunny's middle name.