One of the subjects I teach is "resilience". We do two lectures as part of a general security course, and I added one to a "contemporary issues in ICT", and a seminar in "civic cybersecurity".
We consider Carrington/EMP events, extreme weather threats, political shutdowns, emergent faults and black swans. As responses we look at the technology of mesh nets, ad-hoc community networks, emergency broadcast systems, regressing from DNS to local hostfiles, local storage nodes for things like Wikipedia snapshots.
You have to split the problem into three fundamental categories, storage, communication and processing.
We generally assume that telephone systems would remain operational, but that is no longer a good assumption now that DC battery storage on analogue lines is phased out for fibre or co-ax. The biggest threat we've identified is "cashless society", which would be a total catastrophe whichever way you cut it.
Local storage is cheap and solved. Most individuals and many small institutions like schools would survive fine for months on end. I have a Wiki snapshot that's 5 years old and still makes great, informative reading, plus old Microsoft Encarta, which is great. I've got about 80GB of books as textfiles from Gutenberg and Archive.org (enough for many lifetimes of reading) I've used youtube-dl to always grab and store videos to save bandwidth (because one almost always needs to review them), so I've a couple of 2TB drives just filled with interesting talks and lectures.
When it comes to communication that's a different story. We've played around with BATMAN to make ad-hoc meshnets, but any such project requires coordination. Short of walking around the neighbourhood with instruction leaflets and CD ROMs its a huge barrier to bootstrap a community network.
For resilience planning you need to eliminate any devices or software that needs connectivity just to work, or will fail unsafe without regular updates.
Everyone would adapt, just the way we all adapted when the internet become popular in the first place. Both lifestyles have had their pros and cons.