Try imagine North America without fuel for 5 years...?
No phones (including cellphones), no computer networks, no tv, no radio, no cars, no trains, no airplanes...
No delivery of produce from the country side to the cities, no deliveries of farming equipment from the industrial areas to the farmlands...
No schools or education save whatever books and papers you might be lucky to find, either in libraries or abandoned book stores...
A system made up of specialists, who are all bricks in the wall, starts to crumble. It doesn't matter that you have a degree or two in physics if you can't catch your food once the canned stuff have been scavenged from the grocery stores. The most likely survivors will be the generalists, who can do a variety of essential survival tasks. Fishing, hunting, growing crops (without advanced technology) and perhaps a few demagogues who can BS others into doing the work for them.
Without an infrastructure in place, we are nothing. I would say, it is quite easy to imagine really