A blanket cure is an unreasonable thing to expect given how little we even understand the cause of stuttering from a neurological perspective. But I'm quite confident that within our lifetimes we'll find ways to pharmacologically mitigate it for a wide range of people. Keep in mind that there are already drugs that have been demonstrated to have efficacy in treating stuttering. It's just that at the present moment, most of these tend to have accompanying side-effects and are primarily designed to treat other conditions. Also, it doesn't need to be a 100% cure for it to be effective. Even a 50-60% reduction in someone's stutter can be a dramatic improvement in their life.