Will ptsd go away on its own?

Surviving PTSD: Ptsd may be overcome by learning new insights into how one defines their experiences and emotions; it can be overcome by learning new coping mechanisms or skills for the ongoing stressors of life; it can dissipate with time; there are really a lot of possible answers to your questions. For me the key is gaining new skills and new insight into past feelings and behaviors.

Perhaps...: About 1/3 will resolve over a few months about 1/3 will resolve over a years about 1/3 will be chronic and last for years...

That depends.: Although milder post traumatic stress disorder may resolve without treatment be aware that ptsd can be like a slumbering beast that can be woken in the future by anniversary events or further trauma. For moderate to more severe ptsd - not getting help is a recipe for problems.

Management: Typically with the more severe cases of PTSD, the medical/psychological is not so much about curing it, as it is about effectively managing it. It never goes away in the sense of being cured. In a way both patients and doctors are students of managing severe cases of PTSD, and never master of controlling it, unfortunately.