I see a slight possibility, but I don't think it will happen. The reason why Facebook and Twitter are so popular is because they are used for social, business networking, and advertising purposes.
On GAG, you will see ads for certain apparel stores, make-up, and dating sites, but once you hit a certain xPer level, you don't see them anymore. Plus, you can cash in a certain number of points to have all ads blocked for up to 30 days (or at least you used to be able to). Granted, the majority of users are not regulars and are just here casually, but I would think that most businesses probably wouldn't be to interested in that, as they want to reach the greatest number of people as they can.