Why do you think the fans won't drink at least the same amount of liquor or beer outside the stadium and then add a couple of higher priced hits to that once they come inside? Second question: what about restricting actual consumption inside the stadium to the public areas rather than permitting it in the seating areas?
There will be all types of reactions and situations but I suspect some won't feel the need to cram three more down on the walk up because they know they can get beer inside. Once inside the line and $8 a throw may limit the consumption. A designated drinking spot outside of the stands seems like the smoking area outside the office door. Who knows.