If there is no doubt it was unnecessarily hit in anger and it hits someone then it will likely be dealt with. If there is any chance the player was prepared to make a shot anyway and just happened to hit it after the call probably nothing.

As you're clearly bringing this up because of Djokovic's default, also bear in mind there is a huge difference between hitting the live ball immediately following a point within the confines of the stadium that everyone should be watching, and picking another ball entirely a good few moments following a point out of your pocket that nobody expects to be hit. He had no excuses whatsoever and no argument that it wasn't entirely unnecessary and negligent.