At the end, Rarity is caught & executed
BUT
Although, she was sentenced to death, she wasn't sentenced to STAY dead, now was she.
It's About Time, the Gates of Tartarus are fairly close to Ponyville
It would be possible to mount an expedition to get her back.
Pitched it to the author, their response was "Rarity was a serial killer. Folks are GLAD she's gone"

Really?
Not Luna, that Rarity saved at the risk of her own life.
None of the rest of the Mane 6, not even the Element of Loyalty, not Spike,
not one of her relatives, not even ONE pony that she helped?
Every pony alive, that's their response, no exceptions whatsoever.
& I thought humans were an ungrateful bunch.

I'd write the story, but I lack the skill
(As a writer, I'm a good proofreader/editor)