This is a bit silly. If you're going for parity with modern consoles (PS4, Xbox One) then it's going to cost more than the rumoured price. It's going to be a similar size+cost of those systems. Even without a standard HDD and optical drive it'll be huge.
I'm sure not parity. But it will be interesting to see how far off. My xBox1 is connected to a 720p projector in my living room. I will buy and connect the Apple TV to it. Since the projector limits output to 720p instead of 1080p, I wonder how much of an advantage will the XBox have. I think games will be good enough.