It is already true that most (nearly all?) breeds of domestic animal are no longer used for food: they are kept as pets, in effect, in farms that specialise in preserving unusual breeds and displaying them to the public, with notices next to the pens explaining how there are only 150 of them left and feeding time is at 3.30pm if you want to watch. The same fate awaits today's popular "production" breeds, whether they are replaced by Quorn or by an improved breed.