I like this "universal Peggy Sue" idea. I wonder if the computronium might be replaced by weird physics.
One technology plausible in a time travel world could be undoing time travel changes by going back further in time and thereby preventing the time travel from occurring. Also, whether the passing of a given moment happens by deterministic or non-deterministic processes could be variable. In order to revisit a specific future you could always follow a particular previously determined worldline to it.
In my weirdtopian extrapolation of this notion, there's a vast set of worlds which trillions of people are swapping back and forth between all the time (with careful tracking of the necessary pasts using computerized transporters), without giving a moment's thought to the fact that they are destroying all of the previous universes they have been to. "Ah yes, my living room is in the Mesozoic era on Earth 12..."
Another related (but maybe less weird) scenario would be a world where time can be treated as a bankable resource. People could go into stasis for a day, then suddenly perform actions twice as fast over the following day, or instantly use up their day in the course of a moment. They would also be free to sell their days, thus getting shoved further into the future, or purchase new ones for productivity and/or relaxation purposes.
Utopia and Dystopia have something in common: they both confirm the moral sensibilities you started with. Whether the world is a libertarian utopia of the non-initiation of violence and everyone free to start their own business, or a hellish dystopia of government regulation and intrusion—you might like to find yourself in the first, and hate to find yourself in the second; but either way you nod and say, "Guess I was right all along."
So as an exercise in creativity, try writing them down side by side: Utopia, Dystopia, and Weirdtopia. The zig, the zag and the zog.
I'll start off with a worked example for public understanding of science:
Disclaimer 1: Not every sensibility we have is necessarily wrong. Originality is a goal of literature, not science; sometimes it's better to be right than to be new. But there are also such things as cached thoughts. At least in my own case, it turned out that trying to invent a world that went outside my pre-existing sensibilities, did me a world of good.
Disclaimer 2: This method is not universal: Not all interesting ideas fit this mold, and not all ideas that fit this mold are good ones. Still, it seems like an interesting technique.
If you're trying to write science fiction (where originality is a legitimate goal), then you can write down anything nonobvious for Weirdtopia, and you're done.
If you're trying to do Fun Theory, you have to come up with a Weirdtopia that's at least arguably-better than Utopia. This is harder but also directs you to more interesting regions of the answer space.
If you can make all your answers coherent with each other, you'll have quite a story setting on your hands. (Hope you know how to handle characterization, dialogue, description, conflict, and all that other stuff.)
Here's some partially completed challenges, where I wrote down a Utopia and a Dystopia (according to the moral sensibilities I started with before I did this exercise), but inventing a (better) Weirdtopia is left to the reader.
Economic...
Sexual...
Governmental...
Technological...
Cognitive...