I like that question, it's interesting. I'm inclined to say no. The phenotype of your personality may change and getting rid of physical barriers that stunt your growth may help you develop other functions. However, I think the preferences are still hardwired into your system (and by functions, I mean Si, Ne, Fi, etc.), independent of phenotypes.
So, for example, if you have social anxiety, and appear shy, then take anti-social anxiety pills (too lazy to look 'em up), you will appear to have morphed from introvert to extrovert. At the same time, you were and still are dominated by extraverted perception (primary function Se or Ne). This would mean that you are and always were an extravert (according to the MBTI system), regardless of how outgoing you appear.
Now, when it comes to conditions like schizophrenia, where the actual brain is messed up beyond "chemical imbalances," I'm not sure. I'm also going to acknowledge that I have no rational argument behind the "hard-wired" theory beyond what I see in chemically healthy persons (which includes the emotionaly unhealthy). Hmmmm, I guess I'm saying it's genetic.
Anyway, hopefully that made some sense.

Hazah!