While I can't speak to Patek policy, everything I know leads me to believe that they would not do this and that you would be unwise to wish it. Changing the dial of a fine watch makes the watch undesirable to collectors, so you would be paying to reduce the value of your watch. If you decided you'd rather have the other dial, you would be better off selling your watch and buying one with the other dial in comparable condition.
I do understand your dilemma. I've been wearing the blue dialed version a great deal and bought another with a black dial, thinking I'd eventually want both. For months, the latter has remained unsized, unworn, and untouched, as the blue is wonderful and often looks black. I'm still unsure whether I have any reason to keep both.
You'll likely be happy with either choice, unless indecision causes you to wait until next week's price increase before acting.
Park