I would argue there are plenty of cat breeds that are fully domesticated. For example, when you get a ragdoll cat from a reputable breeder, they usually come with a contract that stipulates (among other things) that the cat will not be allowed to roam outside unsupervised because a lot of their survival skills have been bred out. In my experience with the breed, there are some individuals that probably wouldn't be completely useless trying to live as feral cats, but I've met others that I'm not convinced even have a fight or flight response.