Sure first you can just advertise inferior goods. The quarterly thirty dollar boots when people can no afford longer the 120 dollar boots which last years. Later you can start advertising cheap credit to cover daily needs. Then the datamining starts. If people can't provide revenue directly we'll collect so much data that some profit generating stream will appear. But eventually the entire sector should collapse as the consumer won't have money to spend freely.
It is. The whole fuel for big tech is being able to sell data, and selling data is only useful for marketing / advertising. At a certain point (that we passed long ago) you get extremely diminishing returns because you're already targeting and reaching everyone. Tbh this will mostly affect Google, where as Facebook's main product is not strictly advertising to people, but changing what masses of people actually think.