Viewing this iFixt article that showed the internals of the new Thunderbolt Display made we wonder if Apple had played around with the idea of putting the AppleTV internals inside.
The current AppleTV sells for $99. Information Week estimated that the manufacturing cost (as of the initial release date) to be approximately $64. I can only assume that the cost of parts have come down so that price is probably a little lower.
And then there are some parts that would not be necessary. There's no need for an HDMI port. No need for an additional Ethernet port since it's already built in. Additional power isn't needed. And without knowing the specifics, I would guess that there may be even more redundant chips or parts that wouldn't be needed.
So for a relatively low increase in cost, Apple could sell the Thunderbolt Display with a 'free' AppleTV built inside.
I would guess that they had thought about this possibility and may have even created a prototype or two. This may even be the reason that there have been so many rumors stating that Apple is going to release an actual TV sometime in the near future.
Building an AppleTV into their Thunderbolt Display would be a great first step in that direction (if that is actually the direction they want to go, which I have my doubts). Before selling a dedicated TV they could have tested the waters by selling a computer display that could be used to view all of your iTunes content without the need of a PC or Mac.