I was hoping someone would bring up the technological aspect of a collapse of modern society and then regrowth. There are two major issues with humans post-collapse being able to create a technological society and these are lack of fossil fuels and surface deposits of metals being used up. Both of these work together to make an industrial evolution type event very difficult and perhaps impossible.
I would wager that there is a different type of technological path requiring less fossil fuels and less surface metals. I dont have any data to support this belief obviously but I do believe that given enough time a human society could develop technology to enable space colonization without the jumpstart of an industrial revolution. This would look like slow generational iteration as opposed to explosive revolution and therefore would be more sustainable IMO.