More Apple TV speculation, this time from Benedict Evans:
Now, consider a new ‘Apple TV’ that’s an HDMI dongle, powered by HDMI so you can just plug it in. It uses wifi direct to advertise itself such that as soon as you plug it into the back of your TV, your iPhone pops up and tells you it’s available. No need to enter a wifi key, no need to fiddle around with an keyboard on your TV screen. Maybe it uses peer-to-peer from then on, or maybe your iPhone tells it the wifi key. And to get the cost down, all it does is Airplay (which Apple has promoted to front and centre of iOS 7 by putting it on the control screen panel). So for $50, any TV becomes a remote display for any iOS device.
An HDMI dongle without any other connections sounds futuristic and cool, but it won’t happen. It doesn’t fit into Apple’s game plan. Apple profits off device sales. If the Apple TV is a dongle, it ceases being a device and becomes an accessory.
While the current Apple TV is better in a household with many other Apple devices, Ben’s hypothetical TV requires a household with other Apple devices. That limits the market while simultaneously reducing the margins on each unit sold (half the price means lower margins). Not good for profits.