Apple, Google, & Amazon have content connected boxes in the case of Google they have a few as they try to figure out what exactly they plan on doing. Sony and Microsoft have their own content connected devices in the form of the Playstation 3/4 and Xbox 360/One respectively. All give you access to basically the same content services; Netflix, Hulu (these are really the only relevant two), YouTube, Vimeo and a few others. In the case of Apple you get iTunes, Amazon gives you Amazon Prime (and a few mediocre games), and Google gives you access to the Play Store (and likely a few mediocre games).
So basically there are three separate sources of the same content, you essentially have the same connected box available for $99. The problem is that the boxes do absolutely nothing special beyond accessing services regularly viewed online, that's really it. Why choose a Fire TV over an Apple TV? Because it can play mediocre games and Amazon Prime? Why choose Chromecast/Android TV/whatever name Google gives their new device over a Fire TV when they do essentially the same thing? Samsung will probably come out with one of their own aside from implementing everything under the sun into their televisions because that's what Samsung does.
The main problem basically every company has had is dealing with an industry stuck in archaic ways focused on business as usual. Cable companies bundling 200+ channels where the regular household watches no more than 20 give or take (to be fair this article is from 2008 which is why theres the "give or take") all while charging obscene amounts will be around for quite sometime. In all likelihood another company needs to surface that competes with Hulu and Netflix offering content not available on either service releasing shows similar to what's done on television. And that's the most reasonable hypothesis that could be provided with regard to the eventual disruption of television.
Whichever service is able to grab a user's attention away from the traditional television model will have begun a new paradigm in entertainment, until then...we must continue down the path of antiquated normalcy.