"Shift to animal husbandry as a survival tactic?"

Sure, as long as you kept them fairly close to protect them. Chickens are the first that come to mind, as they can scrounge for some of their food and like insects. You can increase their protein intake (needed for egg production) by growing maggots in garbage in warm weather, and they will eat a certain amount of fresh garbage, and they like quite a bit of regular grass.

But I think if you're staying in an urban area during a long-term food shortage (where it doesn't come down to people plucking blades of grass for food), maintaining a good stock of vegetable seeds suitable for your area would be your best bet, plus saving seed from the resulting crop (you'd have to let some fruits mature to get ripe seed).

If things got bad, even if you don't have much of a yard, your neighbors would be willing to donate their lawn areas to grow veggies, and help you with the labor and protection.

Just a tip on converting lawns to veggie gardens: Don't peel up the sod and throw it away. Either peel it up and just turn it over so it rots, or cover the area with something that will kill the grass: cardboard, thick layers of newspapers, plywood, sheetrock, etc. That clump of soil and grass has some nutrient value, so don't throw it away.

The two easiest (and quietest) domestic animals to grow for food are chickens and rabbits. Both provide quality manure.

Sue