Wolves would not have evolved into the dogs we have today, because many traits which our modern breeds of dogs contain are not advantageous in a natural environment. For example, labrador retrievers are prone to having hip displacement problems, which means that they become less effective hunters and are more likely to live shorter lives if they contract this problem. Humans bred dogs to have desirable traits for humans, but this breeding has made these 'species' (in order for something to be considered a different species it can no longer produce offspring with its predecessor) has made them dependant on humans. They would simply be outcompeted by the natural wolf because it has evolved into an apex predator, which is designed to thrive in its own environment. Also, evolution cannot occur in one animal. That is a mutation, and will not be passed on, unless it provides an advantage which allows that specific animal to breed more.