Ultimately people have a specific amount of disposable income regardless of how much advertising you throw at them, so the market will rebalance. There might be less advertising overall, which is a good thing for many reasons but one of them would be that the advertising that remains becomes more effective. The mediums you mention currently don't have the viewership because all attention is consumed by social media - this may very well change.

In addition, the issue only applies to the common definition of internet advertising. Advertisers can still produce first-party content just like any other user on the platform and people will like/follow/share it if it's useful or entertaining to them. Product placement will still work, and so on.