Beyond the dinosaurs being the big spenders on TV, there's no way digital advertising as we know it today will replace TV advertising. Creatively, you really can't even compare the two. A TV spot is the opportunity to make someone laugh or make someone feel something – anything. A banner ad or a spot with a "skip now" button is not going to do that. You really can't tell a story (as cliche as that sounds, its true). Digital advertising has less creative opportunity for the people making it and basically no reason for anyone seeing it to care.
This is why Snapchat and Facebook starting to really figure out video is so huge in adland. As attentions shift there and it starts to house real content, advertisers will have an actual digital channel to create content people might actually care about.