Sadly I doubt this will have any negative effect on puppy mills in the short term. If anything this might be the biggest boost on puppy mill business in years
I have worked at two pet stores locally, one of them being a pet land, and I would say 99% of the puppies we purchased and sold were from normal families, not puppy mills. During that time the worst cases of puppy milling I heard of were online operations. It is what I expected thought. The reason pet land wont sell puppy's anymore is because they overcharge for their puppies. Kittens too. Why pay 600-1200$ for something I can get on Kijiji for half the price and the same breed, probably even more selection. So there is a large and established market for dogs online. And too top it all off I would imagine most true puppy mill owners are too greedy and/or smart to sell dogs wholesale to most pet store chains in the first place. Since most pet stores will only buy dogs for 1/2 to 1/3 of the value they will retail for. I also know you can spot a mill owner from a mile away if you know anything about dogs. The dogs are never ever as healthy or spunky as dogs truly cared for. If we brought puppies from one person more then once every year or two we would go to check out the place they were bred.
I should add that I do know some pet stores sell mill puppies. But I feel that more often then not the pet store managers either cares for dogs and or life enough to not buy them from a mill since he knows the conditions they have suffered, or would not want to associate the store with milled puppies since they are generally much less healthy then a properly raised puppy. Too bad that not every pet store owner/manager has a conscience :/