In the last couple decades food manufacturers have become very creative with substitutions. "Meat" is no longer meat, "bread" is a brew of chemicals and even the "blueberries" in a lot of foods are really bits of flavored figs.
But it is comforting to know that sausage is still sausage. No matter where you go, in the cheapest, most disgusting fast food factory around, sausage is still serving the same old purpose of taking disgusting bits of leftovers, grinding them up and putting them into patties so you can eat it without thinking about what it is... just like it has been for centuries.