Wouldn't this involve losing all communication grids and access to bank accounts? That'd be pretty disruptive.

I suppose the immediate challenge would be how to organise food 7 days out if we got hit by something like that. Assuming people put in a desperate effort and sort that out somehow, then the medium term problem would be something like a long period where effective communication is gone and any JIT systems fall apart. COVID shortages times 100 possibly.