Well…..
The Silver Fox is one of the breeds listed as ‘Critical’ by The American Livestock Breeds Conservancy (albc-usa.org/cpl/wtchlist.html) so if people don’t specifically breed them, they will die out.
People keep animals for different reasons. I admire people such as yourself that are compelled to rescue animals as there are many animals out there in need of good homes (a rescued Australian Shepard has become a new addition to my family in the last couple weeks) but the diversity of species (be them plants, animals, or any living thing) is dependent upon people that are willing to seek out the creatures that are in need of active preservation.
I live on over 2 acres in a fairly rural area outside Portland, OR. Though it’s a stretch for the house cats (not much in the way of mousers), most of the animals around here earn there keep. My free-range chickens lay regularly and occasionally find themselves in the stew-pot, the dogs help run off predators and my daughter uses them to herd stock, the planned goats will provide milk for all kinds of cheeses, and the rabbits will also contribute. After all, as stated on www.rarebitsandpieces.com “…the Silver Fox rabbit is an outstanding dual purpose breed for - Food, Fancy and Fur.”