If you got a Kit Fox (that's a baby), you might be able to domesticate it, but it might still have that wild instinct. It took many years for humans to selectively breed cats and dogs to domesticate them, and look at how many "problem" breeds we have of both. Since I have heard of no others having a Fox for a pet, I'd say it is not likely that they would be a good one.
No! No! No! No wild animal can be domesticated, and to try to habituate them should only be attempted by people trained to do so, and then only for very specific reasons, such as one who's been injured and cannot be returned to the wild. It is very difficult to provide a wild animal with the environment in which they can thrive. It's almost like thinking you can have a fish live out of water if you just love them enough. Enjoy them in their wild environment and don't try to make them something they can never be.