The reasonable counterargument to this is that you are comparing the actual pain and suffering of real, existing animals, to the potential life of animals who d

The reasonable counterargument to this is that you are comparing the actual pain and suffering of real, existing animals, to the potential life of animals who do not currently exist. "What happens if we stop raising livestock?" means that no further cows will be born to a life of suffering. That's...really it. Those hypothetical animals aren't floating around in the aether wishing someone would just have let them be born.