Breakdown
Here are a few notes and explanation why this will never happen.
Margins
Almost all of Apple's product and business operate at very high margins, certainly much higher than most of the electronics industry.
They can charge these margins with the Mac because of its control over both HW and SW with the Mac, and because of (at least the perceived) the benefits over Windows.
Apple can charge high margins on the iPhone - JUST because the way the cell phone industry works. The phone companies actually pay for a lot of the phone real price because they lock you into a 2-year contract. That brings the (perceived) price to the customer down to something reasonable. But Apple still makes its margins.
And just to be complete...
The iTunes store is a cash cow (once you allow for the infrastructure to run it). Apple was able to effectively create an ecosystem which encompassed all major contents providers (record companies) because there were only like 6 record companies to deal with! Plus Apple struck these deals at a time when the music business was in tough shape. The music industry stuck its head in the sand when it came to the 'net, and saw its revenues go in the tank. Apple provided them a way to utilize the 'net and make money. (BTW, Lets face it, a big part of the success of the iTunes store was due to timing. If Apple tried to do it sooner, the record companies would not have yet perceived that they had a REAL problem and they never would have signed up. If Apple waited longer, too many others, i.e. Amazon, would have been in the market already. Apple's timing was perfect.)
Now, regarding an Apple TV...
Apple would never be able to directly compete against the Samsungs, Sonys, Vizios, etc. They would get killed on price. First off Apple would NEVER consider getting into a HW business with razor-thin margins like most HDTV manufacturers deal with. So Apple would not have price points near that of the current suppliers.
So, you are thinking .... what if Apple were to come out with something so cool, so awesome, so much better, that people would pay a 40% premium for a TV that came from Apple.
That's a lovely thought. What if Apple had an Apple Store for TV programs?
That would be really tough to do. Sure, Apple has done something like that with MOVIES, but again the movie industry is fairly self-contained like music, you can get deal with the 5-6 largest distributors and basically provide 95% of the retail content out there if you want.
But BROADCAST TV and CABLE TV are different from movies. There are many many players involved.
So the only real advantage that Apple could provide in a TV (to justify its 40% margins) would be:
Ad-free content - Which it cant do because there are too many content providers to deal with.
Another possibility would be that Apple would make it easier to hook the TV up to stuff. But let's get real. Apple would have to defines interfaces that work with hundreds of existing BD players, stereos, etc. Those standards are defined. Plus, lets REALLY get real .... although hooking up stuff can be a pain, its a non-recurring pain. People go through their challenges getting everything to work, but once its hooked up and it works, it works, and the connectivity problem is nullified. People wont pay a 40% premium just for this convenience.
So, there you go.
By the way, for you newbies out there, there already WAS an Apple TV many years ago. It tanked.
So as fo a NEW incarnation of an "Apple TV" ...
It will never happen.