What Would Happen If Regulators Blocked Ad Tracking Entirely?

Ad tracking has become one of the most common tools of "modern advertising". But as regulators start legislating more and more against it (and some big tech companies taking stances "protecting" us from it), one has to wonder, what will happen to the advertising industry? Do we go back to the bright ages of creativity? Do small businesses lose a key competitive advantage? Is it all a storm in a teacup anyway and we end up simply using contextual targeting?