Definitely there is hope for him. It is good that he is beginning to trust you, in that he will listen when you speak, and tell him to do things. Three months is not much time at all, and you are already making progress. Have you thought of taking an obedience class with him? It is not to correct any disobedience or anything, but just something to help you and he gain confidence with each other, and with the rest of the world. His intelligence means he is going to be a bit slower to trust likely, as he is remembering all the bad experiences in his past, and waiting for them to happen again. Getting a dog mentally healthy can take a lot longer, but will be very much worth it.

How old is he?

If he will accept one (may be too soon for it) give him a belly rub from me, okay?