If it's more attractive, provides better functionality than other TVs, and the cost premium is not too high, then lots of people will buy it. I may be one of them, should my current TV die.
That's it right there.
If it is more attractive than what? There are hundreds of current choices out there, and we've gone through the full list of different TV designs on the market. For Apple to develop a TV which truly is different in appearance... I'm not sure how they would do so. Televisions aren't exactly a new product just come along in the last dozen or so years.
Better functionality certainly is a no brainer, but then gets stupid. TV functionality (Smart TVs) are certainly being touted by Samsung, Sony, and Sharp. For the most part, they suck. This is where Apple can excel, but the problem is that a good AppleTV already does this. A better product (list one here) can do it better. In five years, today's AppleTV will be a couple of generations old at least. Do you really want old 'smart tv' in your TV? If they offer a spot to put the AppleTV directly into or on the back, or a smart network connection to an externally upgraded AppleTV, then it's still just a new TV you're buying... not really any smarter, except it likely will have some proprietary integration by Apple.
Finally, the cost premium is one Apple is known to not follow. They have high prices. The thing is, they usually have a significantly better product in some aspect. I'm struggling to see how a TV itself would offer this upgrade aspect.
That said, I certainly have more than a few ideas myself...
A wireless HDMI box which can connect to the output of any HDMI enabled source and can be paired up with any TV in your home, free of wires! This is wireless HDMI matrixing. It means that controls from your remote are sent to the source that is currently selected automatically. It means that the name of the source you select is automatically populated to your display. It means when you hit 'source select' on your remote, you get a list of ALL the sources in your home which are available, perhaps with a list of whether or not they are in use by other rooms.
Add that capability across the home and into surround and stereo areas. So, a box which can grab audio and send it to speakers without extra wiring. Plug it in, pair up your sources, and you are done.
I've seen almost zero movement from manufacturers down that path, and it still doesn't require me to replace my cheap LCDs or my nice plasma to get most of that functionality if it was done properly.
It would really suprise me if Apple revolutionizes the TV industry, but I would still be thrilled to see it happen. I do like their inginuity.