You've put your finger on what I find difficult or unproductive in some of the analysis here.
Of course, systemic failure may doom any response - I don't know.

However, if that is the working assumption then for a start the analysis tends to jump around from point to point of difficulty, by-passing often fairly simple remedies to particular issues.

I am also not a big fan of power down solutions - systemic collapse would certainly seem probable together with mass deaths under those scenarios in my view.

Considering that heating and air conditioning could be done with a fraction of today's energy inputs, and so could goods transportation and personal mobility, together with feeding the population with a much healthier diet with less, better quality meat, then the obstacles seem primarily institutional.

Focussing largely on the interdependencies rather than biting off bits that are chewable may make life too hard! :-)