For the first few years that we had cattle we raised lawn ornaments. We didn't milk them, or eat their meat, or use them for pulling. Even though Milking Devons are extremely rare (between 1,000 and 1,500), just breeding more of them isn't what is best for the breed.
To be worth saving livestock has to have utilitarian value. Our Devons perform their historic functions of meat, milk and draft.
Taste Devon beef, milk or cheese and you'll understand why they need to be preserved for future generations.
I believe that working cattle, oxen and handy cows, have a future in forestry and farming. The triple-purpose house cow is easier to maintain and far less costly than a tractor.