Vegan

A quick and dirty internet search says that a typical farm pig lives around 7 months. So you could ban every meat pig product in a year, stop breeding new pigs and just murder the old ones for meat and you would have no problem at all. So a grace period of less than a year is needed and you wouldn't have this problem. (I also seriously doubt that most farm pigs would be able to survive in the wild, but for that i am not knowledgeable enough. But e.g. modern chickens have a huge calcium deficiency which makes them not very suited for wildlife, there was an study that the average chicken at any given time has three broken bones.)

Or to put it in another way, we have to replace all farm pigs almost twice yearly anyway, so let's just stop replacing them.