While some view online ads as a zero-sum game — online gains represent offline losses — I generally take the view that online advertising is shifting dollars from other media, as well as helping grow the offline advertising pie (at least a little). Looking backwards, that has been the case in other periods too, like when TV hit the mainstream:
Every other consumer medium lost share from 1950 to 1960, yet every
medium still managed to gain revenue during that booming decade. Even
radio, most threatened by TV, managed a small gain.
While I’m not convinced the effect will be as pronounced this time, I think we’ll still see a general spend expansion.