That's why they'll stop making all their other products - because not everyone will buy them.
What would really hurt is people not replacing their Apple-branded televisions on a "regular" basis. Many folks replace their iMacs, MacBook (Pros) and iPods/iPhones every 2-3 years and Apple depends on that "churn" with existing customers just as they depend on new customers to drive revenues.
Yet even with the move to 1080p HD, 240Hz and 3D, folks are not replacing their televisions every 2-3 years, even with prices in the dirt.
So the sell-through rate for an Apple LCD or Plasma Television would be very low compared to their other product lines and considering that Apple would almost assuredly price their televisions at the upper end of the pricing spread, folks would be even less inclined to replace them on a "regular" basis.
So Apple would strongly be dependent on new customers. And televisions are already pretty simple devices to operate, so it's going to be harder for Apple to make the experience of watching OTA/cable/sat/DVD/BRD content better or easier.
Where Apple can improve the experience is through applications and games via iOS devices. And by doing that though a $99

tv that can connect to most everyone else's televisions instead of a $1999 Apple-branded television, Apple can encourage existing customers to buy new product. I bought a first generation

tv at the reduced $150 price when the new model was released, but a year later I now have the $99 model, as well. And if Apple releases a new

tv in September with more powerful CPUs and better graphics to support new functionality, I'll thrown down another Benjamin.
But if I had bought a $1999 Apple TV and the new features were only available with a new $1999 Apple TV, I would have to decline - and bitch about Apple obsoleting my investment, of course.
