With everything going online and the internet going to wifi, all wired networks will soon be a thing of the past. Wired networks require extensive infrastructure which is expensive both to produce and maintain. Wireless networks, on the other hand, require a limited amount of equipment and now that they are increasingly able to provide the same services for less, there is no need for the higher cost, outdated wired networks like cable television.
I don't think Cable will disappear entirely until the older generation dies however it's obsolete. Most shows can be streamed and with the advent of YouTube all those years ago much of the content of the internet has been modified to cater to specific audiences and therefore is not subject to time frames, constraints, or even contracts.
While I may not be a subscriber to HBO, I don't think cable TV is going anywhere anytime soon. True, we can stream almost anything online these days, but nothing beats watching a live event, be it a sporting event or TV show, on the big screen. And in some cases you'll get higher quality and pristine audio.
Obviously, internet is growing and it will keep continuously growing, maybe until no end, but there a huge audience that still haven't interest to do everything through the computer. And, in 3 years, this audience still will be there, I think to get at the point where cable tv will be obsolete should takes more than three years, perhaps ten.
I do not think that cable will obsolete so quickly. That would require lots of change in home equipment and infrastructure which cannot happen overnight. Most people can't afford to get rid of perfectly good equipment at the drop of a hat. I think cable still has a good 7-10 years before it disappears.
Cable television has been around for many years as it is much cheaper and many people prefer to use it because of its convenience and availability.A large number of people have subscribed to it and recent reports indicate that most of them chose the cable television over the HBO one.