I get this question quite often when meeting a new client, and while I've gotten more used to it, I am always slightly thrown. Words are important, and the shelter where I cut my teeth is well-known for giving dogs of all temperaments a chance. "No hope" is a pretty far descent into deviant behavior for me, and almost never what I encounter with private clients. I find it very telling when people use that phrase because of the emotions that are so clearly behind it.
What these anxious, desperate dog-owners are really asking is, "Can my dog change?" The short answer is yes, and when people ask me if the dog has hope, this is always my answer. The less-clear, more honest answer is, you'll get out what you put in. Behavioral modification is typically a slow road and requires commitment, consistency, routine, and management. The more a client is willing to put these concepts into practice and keeps them there, the more positive the prognosis for change in the behavior.
The reality is there are many other contributing factors determining whether the dog will change. Past success, age, and instinct can drive a dog to repeat unwanted behaviors, and the owner needs to intervene at key points to introduce an alternative. In a perfect world, this management would take place 100% of the time the dog begins to engage in the behavior.
I literally have never heard of any human being who has been successful at this level of consistency in any area of their lives. Maybe I know a lot of messy people, but they also have some pretty happy dogs, and have gotten acceptable results with behavioral modification. As someone whose job it is to help people reach goals, I have to be realistic in setting up expectations for my clients - both from themselves as well as their dogs. I can explain all day how to get an end result, but if your dog requires eight hours of repetition to be reliable around triggers, you probably aren't going to put that level of work in. And that is 100% ok.
I do encourage adjustment of expectations, especially over the course of modification. I do tell people to be realistic - about success, timeframe, commitment level. I do tell people to prioritize. I do tell people that management may be a constant in their lives.
I have yet to tell someone their dog is without hope.