The available worlds looked pretty grim. They had little to offer him because he had little to offer them. He had been extremely chastened to realize that although he originally came from a world which had cars and computers and ballet and Armagnac, he didn't, by himself, know how any of it worked. He couldn't do it. Left to his own devices he couldn't build a toaster. He could just about make a sandwich and that was it.

-Douglas Adams, The Hitchhiker's Guide to the Galaxy

Arthur Dent realizes that he, as an individual, is pretty useless for improving a society, but he can make a damn fine sammie.

You're running off the assumption that the survivors know useful information and that theyre also able to utilize that useful information plus be able to source needed materials since they wont have travel

I think we're assuming books will continue to exist.

I think one of the real marvels of civilization is the redundancy of information. For every college course you've taken there's a text book, and there may have been dozens of physical copies of that book used in your class, but also for many other classes at other schools that taught that same subject. There may have been 10,000 copies of that book in circulation across the globe, in many different countries.

It's not impossible to lose information forever, but we've put in some really strong defenses against that really happening. There are a lot of libraries in coastal areas which could flood, or big cities that could burn after wars or riots. But there are also plenty of libraries in small towns, and at high elevations. Correct me if I'm wrong, but I believe Aspen has a public library for instance, and so do some of the small towns nearby that you don't know the name of.

Likely progression is simply that food gets expensive, and is grown indoors. Technology doesn't need to fall, though when slaves are not needed, soylent green is a "utilitarian" use for them under rules based world order. Food capacity and population that can afford to buy it will match. Fewer people does mean fewer iphones, and more expensive at lower scale.

Global warming, even at 5C, is more about increased misery and oppression, rather than mass deaths over a decade. Wikipedia will survive. The AI tech giants chatbots will explain why you need to die or be miserable until you die.

Just for clarification, I don't think it'll be fast. It will just be faster than without it.

Also, I think we'll hang on to a lot because the survivor base will likely be made up of people from all walks of life. STEM Professionals, teachers, carpenters, you name it. And as long as we learned our lesson about religion, we'll pass that knowledge on.