The POTS diagnosis is often considered to be more of a constellation of symptoms, rather than a specific disorder. That being said, the chances of 'complete recovery' or simply 'outgrowing symptoms' vary greatly from patient to patient. Some will improve over time, others will worsen, and still others will remain the same.
As 'supineallthetime' mentioned, patients with post-viral POTS are generally more likely to experience recovery. However, children and young teenagers may simply outgrow their symptoms entirely upon entering adulthood. It really depends on the situation.
For patients with associated illnesses, (for example: Ehlers-Danlos Syndrome), such improvements are considered to be somewhat less likely. However, that is not to say impossible. You may try asking a doctor about your specific situation...
Additionally, as 'kelly1258' mentioned, some patients have done well with various medications despite their POTS/Dysautonomia.
As for differential diagnoses, there are conditions that exhibit Dysautonomia as a symptom. Examples include: certain Autoimmune Disorders, Addison's Disease, and Mitochondrial Diseases.
I heard the same there is info from Dr. Grubb on it if you research. I think you saw my older daughter and Linda's daughter has done well on Cymbalta.
I apologize for not having citations to back this up but I recall reading that "a decent number" of POTS patients do manage to recover. I don't recall if there was a percentage cited... I don't think it is known that well.
I believe there was mention that those who's POTS hit in post-viral circumstances tend to be more likely to recover like this. Also, those for whom it shows up in adolescence have a decent chance of coming out of it... perhaps tending to do so in their early adulthood.
Please take my comment with a grain of salt... this is what I recall reading but I cannot recall for certain and it isn't very specific information.