I think there's no clear-cut answer as to whether or not PTSD sufferers can ever be said to have completely healed from PTSD. I do believe that some sufferers can eventually get to a point where they don't experience PTSD symptoms ever again, but it depends on a lot of different factors: is there a family history of mental health issues? What was the trauma / how many traumas? How old were they when this/these happened? How did they deal with it / how were they supported when it happened? What kind of support did they have when diagnosed? How successful was therapy? etc. - That being said, even for those who can truly escape PTSD symptoms, these people are not the same people they were before PTSD. For better or worse, they are changed, and it's not just simply an "age & experience" sort of change.
For me, my PTSD comes from 15 years of abuse and rape at the hands of my own father. I've been fortunate enough to have a wonderful, strong mother and two very kind, loving and wise (maternal) grandparents in my life. They raised me, cared for me and encouraged me. Without them, I wouldn't have been able to endure my father. Without them, I'd have committed suicide a long time ago.
I'm not "cured," though, nor do I ever expect to be cured. My PTSD and general depression seem to cycle, though not always at the same pace. I do go through periods of being almost 'normal' for months on end, sometimes even a year or so, but I always cycle back. There are also things about my personality and my outlook on the world that are very clearly influenced by PTSD, but they exist even when I'm in a 'normal' phase. They've become independent of the severity of my PTSD symptoms. I think it's because my PTSD developed as my personality was developing. So, for me, I don't think I'll ever be free of PTSD and its symptoms.