A country wide outage is highly unlikely. As long as there are suitable methods of transportation, you'll always be able to get to a location that will at the very least allow you to access the internet via mobile, which will in turn allow you access to your coins
The winter is approaching and some countries are short of power stations, or rely on power station fuel imported through unreliable channels. During the winter when excessive demand is made on their national grids there are periods when there is insufficient electricity to supply the whole country. Some areas have complete blackouts, and others have reduced quantities of electricity transmitted to their homes. For very big countries it's a long drive to get to another area with enough electric to access the internet, or a working ATM.
In that situation fiat is the only real way of buying things in the short term, but most shops would be shut anyway as their tills run on electricity.