For the end user, this means that when you plug the USB stick into your TV, the streaming copy of Troll 2 you just rented from Amazon (for instance) will appear as a file that you can click on and play, as if it was locally stored.
Whether products like the GameStick will cannibalize the traditional console business is an interesting question: with a developed TV-app ecosystem, this kind of plug-in smart stick might conversely challenge the Smart TV business, with a dedicated gamepad as a bonus.