I can't see a major shift until those who are now somewhere around 30 to 35 and older are no longer a major factor. And when watching TV online becomes
the way to watch TV, it won't be what we think of as watching TV. In fact I question if that happens if the actual TV will be as popular.
For many to most the people growing up now and using online primarily they do not watch programs. They watch clips of programs. Even the popular Tonight Show with Jimmy Fallon is not watched by them, they watch clips on Youtube, often by "subscribing" to it. Others use "Trending sites" to watch clips of what is deemed popular or trending. If something particularly interests them they may follow up and watch more of that episode of a given show. Same for shows like the Bachelorette and many others. And importantly much of the time no TV is involved it is done on smartphones and tablets.
Watching movies is different, and with HBO and Showtime becoming available for those without cable subscriptions I wonder how that will impact Netflix etc.. And movies is where the TV still is important and using Miracast, Sling, or Chromecast keeps the TV relevant.
The way most of us older than that watch TV is entirely different and in no way will most change unless they just can't afford the traditional way or don't really watch much TV anyway.
Two other things, if someone lives at home or even visits often with their parents who has traditional TV (Cable, Satellite) then I don't believe any statistics that they only use online.
Also, when push comes to shove and Cable/Satellite really has to do something to stay in business we don't know what that could be, what technology is coming that may make them more relevant at time goes on.
And a third thing (Ok I lied three things) living in two states, with totally different climates and using two different internet providers, I don't see where online is as reliable as Satellite, or perhaps it isn't always fast enough in some (not all) areas to watch using streaming to a TV.