Probably they could be used for rebreeding. Maybe by crossing a Bull Terr with a Manchester Terrier. I mean, they are the closest relative of the Black and Tan English Terrier, and so to the white English Terrier... The problem is the Temperament, and a extremely dog aggressive dog doesn't fit in the world of our days, it would just encourage trouble, if the extreme Gameness would be preserved. It would provoke the ban of a developing breed...