Heirs to genocide: a thought experiment

I am tempted to write an alternate history in which all sufficiently white people of, hmm, maybe 1800-1850, or around World War I, are whisked off to a humanity-free world, and then deal with their society's collapse. I'd a MacGuffin of some kind to justify the piecemeal shifting. Purity-obsessed aliens liberating what they regard as the dominant society? The Taiping Emperor is right, and when Jesus returns to establish the new celestial kingdom, He's bored of white people? Maybe it doesn't need an immediate answer given well-defined effects.

I sort of feel in the mood to write a horror story about the death of a civilization, and what prospects there may be for better in its wake.

Thinking about writing

I did some fiction professionally back in the day, and it's another casualty of the big hole I've been in for the last few years. But between getting my gender identity in order and the current incarnation of Racefail: This Time It's Even Hairier, I'm really feeling the desire to get some prose laid down. Ever since a friend introduced me to Eduardo Galeano and his astonishing Memory of Fire trilogy, I've been craving some vignette action. Now you've been warned, in case anything like that shows up here.

Secrets of composition revealed!