With the current trend in EU I think it could happen that they regulate web-advertisement if it becomes too much of an issue. But there's loads of money in the market - so I would expect loads of lobbyism.
This may just be some inevitable fact about humanity. We’ve seen this sort of regulation and ultimate centralization of every single communications medium going back to the printing press. When I was younger, I legitimately believed the web would be different. I thought it would be a decentralizing, democratizing force for peace in the world. Now it seems destined to be the opposite of those things: a centralized tool for polarization and control.