Oddly enough a friend of mine’s daughter just made an atlatl, which looked pretty lethal in the video I saw. I suspect she used modern tools to build it though.
Nuclear would dip for a time until we developed a way to burn spent fuel in more advanced fission reactors and or created viable fusion reactors for power. In the meantime more of a mix of solar and wind would be advanced. Long term I have no doubts that liberaltopia would continue to develop nuclear, we still need that for more remote locations on earth with less sunlight, and we’ll definitely need it for our eventual expansion to Mars and beyond. Solar is not going to cut it that far away.
I actually do realize that! However times have changed, and I believe that when libertopia realizes that solar and wind power alone aren’t sufficient to provide steady power in the amounts needed by modern society (yes, I said it), they’d scramble for another clean(-ish) alternative and find nuclear.
(And as noted, the only reason I don’t think conservatopia wouldn’t do the same is that I believe there are profit incentives to keep digging up and burning fossil fuels until they find a balrog.)
IMO, what would happen is if there is still contact between the two populations, there would be some people in both camps that are just a little bit lefter or a little bit righter, and therefore one day one member from the right camp would point out how left some members are or one member from the left camp would point out how right some members are, and all the other members who believe they are true leftists or rightists would travel a little bit further in that direction etc etc if people decide they want to disobey this they will be imprisoned or “re-educated” etc etc until one day we have the same result on both sides - two fascist states. If there is no contact between the two populations IMO they will settle down to a different equilibrium point, both towards the centre.