Apple, no doubt, has a lit of imaginative and talented people and comes up with a lot of need products.
The issue with TV is not can they make a cool TV; but where can the come up with a game changing (and very profitable) product? IMHO, that's not the TV but the content delivery mechanism. If Apple can move people off of cable and into an iTunes ATV subscription model then they can take a cut out of the recurring revenue stream rather than a 1 time TV sale. Moving to that requires a lot of pieces to fall into place - content providers willing to give up steady cable revenue for uncertain subscription revenue; ISPs willing to sell truly unlimited (for all practical purposes) high speed access (and since they often are cable providers as well be willing to destroy their cash cow for a much smaller dumb pipe revenue stream) and consumers willing to cut cable - not the tech heads but the average cable buyer who probably doesn't even have a Mac and to whom apple is the iPhone.
Not easy, but they may just pull it off. If so, we're talking a seismic shift in the world of television - similar to what TV did to radio in the 50's and how cable changed viewing habits in the 80's.
SIRI is nice but until the latency is equal to or less, and it recognizes various voices (anecdotally I know a number of people with issues because of accents) is more of a curiosity than something which will replace remotes.
The real problem with a TV is that the real innovation comes in the software, but the product is a longer term durable good, especially if Apple prices it like they do other products at the higher end of the spectrum. The life span means older TVs may not be able to do what new ones do; with consumers unwilling to shell out a lot of money when they have a perfectly good existing Apple TV and thus get frustrated that it won't do things new ones do.
In addition, while Apple does neat industrial design, existing manufacturers can produce TVs that look as nice and are as capable in terms of display, making it hard for Apple to command a premium on design alone; unlike for Macs/iPhones/iPads where the design is coupled with software that makes the device compelling.
the ATV, OTOH, overcomes most of those limitations - it's cheap, works with most newer TV's, and gives Apple an entry into the content market that they can build on and show content owners there is money to be made.
Can they come out with a TV set? Sure, but I don't find the reasons all that compelling compared to opportunities elsewhere in the broader TV market.
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The question is - are there enough people that want, and will pay for, higher resolution content when they find today's content resolution sufficient? Once you get to a certain point, better is hardly noticeable; so is 1080p so much better than 720p, for example, to warrant replacing a bunch of existing stuff?
I think the interconnectivity between ATV/iPhone/IPod is a much more compelling area to explore.