It's mainly DCI that will take the biggest hit from the legislation. The majority of those drinking on the Promenade are drinking beer. However, also affected, but not mentioned, would be the Sleazy Mart. Consider:
Rock decides to hit Northgate but doesn't want to cough up the money in the bars. He figures he can just hit the Sleazy Mart for a suitcase for cheaper. No problem! Grab the suitcase and head to the promenade with everyone else. As he procedes to get totally sloshed on his suitcase (after sharing a few cans with the crowd, who happen to be underage), he realizes that it's time to break the seal. Damn, everything's packed. Oh well, Fitzwilly's is right here, so that looks good. He shows his ID and walks in like every other patron. After using the facilities, he heads right back out to his spot on the promenade for a few more hours of drinking. At the end of the night, he hops in the pickup and heads on home. During the drive he swerves to miss a dog in the road. With his impaired judgement, he does miss the dog, but also wraps himself around a tree. In the end, who is liable for Rock? Himself? Of course not; not in today's society. From the moment he stepped into Fitzwilly's and used their facilities, he became their responsibility.
A scenario I've made up? Hardly. Friend of mine works at Fitz's and relayed this very situation to me when this discussion first came up this summer. At the very least, it's food for thought.