/diy/ - Do It Yourself

I am writing a book about life after a massive destruction of human life.

I need your thoughts on some end of the world scenarios. In the first one, there has been some sort of fast plague that leaves only one thousands percent (a ten-thousandth) of the population alive. It happens across the whole planet within two or three weeks. Bodies everywhere.

It would seem that there would be plenty of food for a very long time (New York City would have around 80 people. All of Vermont, New Hampshire and Maine would have 30. Japan would have 1,300 people). 5 years, easy. One would have to leave the cities, obviously, because of all the bodies, disease, etc.
Seems like the grid would have to go down. Certainly there could be people that would know how to get some major shit (get cell service, internet, petroleum products, sections of the grid) going, but it seems unlikely.

I am not some weirdo prepper that offends people on diy, I am just writing a book.

I don;t need to know ways to survive, I'd like your thoughts on what life would be like after an event like this, and how people would react.

What do you do when you have a question for /diy/ that has no point in being in /diy/? You guys are the audience I want to answer said question, but this is the wrong board, in theory.