http://www.bbc.com/news/world-europe-34443189
My friend told me her landline phone still doesn't work. There are no phones and no Internet in most of downtown Cannes. Electricity has been fixed quite rapidly, but for 2 days, the mobile phone networks were down, so no bitcoin, and no credit cards either! All the shops couldn't handle any transactions.
The only thing which kept on working was the fiber optic network, I guess because that's the newest.
The whole thing was very local. Everything was fine a few km North, but this shall reminds us that if there's a serious emergency, cash is the only safe option.
That wouldn't be a major issue in tight, local communities, where people know each other. They could just settle payments later.