The worst case scenario should really be defined by just how long will the internet be down.

1 day is an inconvenience

1 week is major hurdle but can be overcome

1 month and people may start being laid off because they can't do their jobs and clients are cancelling services that they can't use

Now how many people over-saturating an internetless job market will it take for food, water and shelter to become a problem is something to study.

This may be an exaggeration, but since we are considering worst case scenarios.