Of course tyoes can change, though I think I have always been an ESTP.
Even from childhood, I mean, I my parents have told me how I always insisted getting my own way, and generally I did get my own way. I remember one story in which I deeply desired a hat and I simply refused to move from near the store and I put myself on the ground and started to yell, and finally they had to get it. Which is pretty much what I do these days, besides the yelling.
Maybe I was a little bit more introverted when smaller... I wasn't exactly popular, but still, I had a lot of acquaintances. As far as I can remember, besides mentally "growing up" there haven't been many changes in my personality.
I have had moments when I told myself I have to make some changes in my personality, however I think I simply refined the way I use functions, not changing my preferences. I don't know how to explain better, but even if I decided I didn't like who I was, eh, well I did like who I was, but not how others saw me and that was what had to be changed, not who I was. So saying that you have changed your personality... it might be true, but it could also be simply adjusting it to fit into the society, which is not exactly changing it.
Heh, I don't know if you understood what I was trying to say. Anyway, the point is that probably, deep at heart you probably never change

), only at the outside, because that's how you want to be not how you are.