If you are living in a city that depends heavily on outside resources to function, you may well be doing best by hunkering down or getting the fuck out.
As time goes on, people who don't have resources and don't oknow how to produce them would become feral. Most people in big cities don't even know how to plant basic food or which fruits can be eaten. A person with these skills could go to the desperate people and ask them to worrk together. You may think that staying in, by yourself, with guns would be a successful strategy, but it would not. The community around you must be stable, too. Sometimes, that means teaching people basic skills, so they focus on productive actions, instead of destructive actions. That's how I see it, anyway.
Feral, no. Humans without resources will do what they need to in order to support our families. Nothing feral about that. Doing what you have to in order to keep stability and feed your kids is and should be encouraged. The cities are full of competent, intelligent people who can and will be able to support themselves, but the thing is that there just isn't enough ability to produce or bring in food without the support of the rest of the farming areas delivering food on massive trips with huge trucks. It's not the people that are bad, we are the ones who formed those cities and built ourselves from the ground up, it's the nature of the changing environment.