It's a crapshoot which way society goes when the infrastructure disintegrates, but Lord of the Flies is definitely not a given. Historically people seem just as likely to come together as beat each other apart.
Plus New York City also had a blackout in 1977 that was very different.
>Looting and vandalism were widespread, hitting 31 neighborhoods. Possibly the hardest hit were Crown Heights, where 75 stores on a five-block stretch were looted, and Bushwick, where arson was rampant with some 25 fires still burning the next morning. At one point, two blocks of Broadway, which separates Bushwick from Bedford-Stuyvesant in Brooklyn, were on fire. Thirty-five blocks of Broadway were destroyed: 134 stores looted, 45 of them set ablaze. Thieves stole 50 new Pontiacs from a Bronx car dealership. In Brooklyn, youths were seen backing up cars to targeted stores, tying ropes around the stores' grates, and using their cars to pull the grates away before looting the store. While 550 police officers were injured in the mayhem, 4,500 looters were arrested.... In all, 1,616 stores were damaged in looting and rioting. A total of 1,037 fires were responded to, including 14 multiple-alarm fires. In the largest mass arrest in city history, 3,776 people were arrested. Many had to be stuffed into overcrowded cells, precinct basements and other makeshift holding pens. A congressional study estimated that the cost of damages amounted to a little over $300 million (equivalent to $1.2 billion in 2017).
Everyone on the radio in the 2003 blackout was going crazy predicting the mass looting that New York City was in for (based on the 1977 blackout).
Just like not eating for one day (fasting) is not the same as not eating for weeks.