Humans are very adaptable. If we don't have the skills, we will obtain and develop them when push turns to shove. However...

There are a lot of spoiled rotten people. They will not accept any other lifestyle than what they previously had. These are the ones that will probably kill themselves rather than learn how to farm and raise/ harvest livestock. Even washing their own clothes on a rock down by the river may be too much for them to handle. But, the strong and intelligent will survive. And those are the kinds of people we want to populate the planet, and not the spoiled rotten blood sucking ignorant lazy parasites.

Technology will never go away. We may lose some ground, but it will be regained. We will not forgo electricity and all the benefits that provides. But we can do without the non-essentials, i.e. cable teevee, dishwashers, cell phones, etc.