Once they do that, people will say that pinetar is a competitive advantage. How can it not be one? Sure, most of the reasoning behind it, is for better grip in the cold. However, a better grip can allow you to throw better curves and sliders. Also, what if the pitcher lathers his fingers with a ton of pinetar? That can adjust the trajectory of the ball.
This issue is a slippery slope. I really don't think that the MLB will do a thing. I just think they'll quietly tell the teams, to make sure they tell their pitchers to not be complete buffons out there.