Poor pigs. There major objective to live is going to be abolish.
They will just become laboratory instrument I guess.  

Quoted from deblynn3

Wild guess,  pork was traditionally a fatter meat, most sausage has a lot of fat.. Also pork intestines where used for the cases, so butcher a pig and use his intestines for the casings. Somethings change some don't

Sounds good to me. If the meat is naturally somewhat fatty feeding and/or breeding over many centuries would develop the desired product. Now both tradition and price will allow it to maintain its position as the prefered sausage meat.