what are the rest of the people going to eat?
They will go on the Maduro diet.
Once the animal stocks are gone it may never recover, it takes years to grow a cow into beef, not many place have self hatching chickens, egg layers. most factory farming there are specialized breeding farms and the growing farmers do so on contract, not owning the live stock. It is very fragile.
Production of enough food for the general public? Nope.
Start a breeding program with any neighbors who have any kind of livestock.
Low will you survive? Dairies are mainly automated and many are totally reliant on electricity for lighting, milk vacuuming, cold storage. Chickens all heated building with fans and power augers for feed and water, pigs the same.
I have Amish neighbors, and 3-4 dairies within a few miles of me. One is only maybe a half mile up the road. My chickens free range. I raise the hogs on pasture, but do need some feed to bring them up to slaughter weight by late Oct, early Nov. I could overwinter them, but that brings up a whole new set of problems.
Once ag land is not used for a few years takes massive amount of work to get it back to production.
Goats. No, really, the farm we have was neglicted for 30 years. Bring on the goats! They eat everything, and turn that into meat/dairy. They eat things cows or sheep wont. Their manure helps fertlize the pastures.
Draft city folk to replace farm equipment?
I would rather set up relationships with my neighbors where we all take turns helping each other mow hay (using a scythe), slaughtering of hogs, etc.