Gaming can have a balance on Android TV
So far there have been two models of playing mobile games on the TV, and they all have some pros and cons, so if Android TV is to be successful, it needs to balance the 2.
The first is the AirPlay model. This is really easy to use, but can result in a lot of latency due to the sheer volume of data. It also drains battery pretty quickly.
The second is installing games locally to the device separate from anything else. However, navigating the UI to dig through all those games is usually a pain and it's hard to get devs to make games specifically for the TV.
A balance would be an extension of the Chromecast API. The first time a game is "cast", Android TV will download a special version of the game to the local drive. It would essentially be the game with just a little code to receive commands from a mobile device. The phone or tablet would turn into a controller and only display the controls and menus for the game. Pressing a button on the mobile would go over local wifi and make the locally installed game execute the command. It's faster than bluetooth, and still as simple as AirPlay. It won't be sending the entire display nor will the full game be running on the mobile device so there's less latency and battery drain. And it wouldn't require brand new versions of games optimized for controllers. They can utilize the existing in game controls so devs would be more inclined to support it since it's simple.
Further down the road, Google could add a controller API and make a controller accessory for phones and tablets. By having both the touchscreen and the controller, devs wouldn't have to redo the controls just for the controller. They could use the controller where it makes sense like movement but use the touchscreen for things that require swipes, pinches, or scrolling through menus.