A bit ironic to see Spaniards afraid their natural resource are stolen from them and be made available on the South American market. I mean, it's not like they did the same with Avocado, tomato and so on and so forth. Not to mention all the gold from South America.
That being said, today's Spanish farmers are not responsible for their ancestors deeds. However, true "Pata Negra" ham is actually so expensive, I don't think people who used to buy the real thing will buy the cheap American alternative instead as it doesn't have the Omega-9, taste and status. Only people who randomly bought super expensive Pata Negra and now decide to get the cheap alternative could affect their revenue, no idea how much this would make up.