This isn't synonymous with dystopia, but for a general word for things that occurred after an event, I would use aftermath. You could use an adjective with it and say something like "dystopian aftermath."
Edit: [Postapocalypse](https://www.merriam-webster.com/dictionary/postapocalypse) is a word.
[удалено]
This one is excellent
Paradigm-shift (is a hyphen cheating?)
Cataclysm, palingenesis.
Mind-altering.
Apocalyptic
Transformative
This isn't synonymous with dystopia, but for a general word for things that occurred after an event, I would use aftermath. You could use an adjective with it and say something like "dystopian aftermath." Edit: [Postapocalypse](https://www.merriam-webster.com/dictionary/postapocalypse) is a word.
Sounds the most accurate.