Now, imagine apple making that thin and beautiful of a screen at 32", 42", and 50". They could price them at $499, $749, and $999. People would buy that.
There are 2 things they could do to really pull people in - make TV easy and put iOS apps on your television.
Make TV easy - have a beautiful UI that makes it easy. Less clutter, easier to read channel guide. Simple setup. Etc. Maybe channel search via Siri. "Siri, I want to watch Fringe." And Siri finds you that episode via maybe a built in DVR, Apple's catalog, Hulu plus, or the cable company's on demand stuff.
iOS apps on your TV. Seriously, $1 games on your TV. Even $6 premium games like Infinity Blade. Compare that to $60 games like Halo 4 or even "cheap" Xbox 360 games at $15 or so. People would go bananas for that. The trickiest part for apps is the control mechanism, but for games, most of them could be made to use a game controller similar to what OUYA is doing.
If Apple can get those two things right, they will be able to charge a real premium for a TV. The reason TV's have low margins right now is that they have no value adds or differentiation. It's hard to justify spending $1,000 on a "smart" tv when a $400 tv has the same picture quality for the most part and every $50+ add on box and blu ray player has "smart tv" apps like netflix, hulu, amazon video, picasa, etc...