There may be some hidden performance in there that we may get "unlocked" for free for for some $$ after the cars have been out and about for a bit. Fun future Elon tweet "You wanted a P? You had a P all along! Just put your CC number in the screen."
I don't expect, at least in the early versions, to see a battery unlock, pay or not. To me, the different mileage on the warranties between the standard and long range versions says that the standard battery isn't a locked variant of the larger one. If it were it should have even greater longevity than the larger one.
That may change, however, as production continues.