This is short. Google TV is pretty good but it isn't spectacular because there are other platforms out there that does much of what Google TV offers. And if Apple's supposed HDTV isn't awesome, it will fail. In essence, Google TV has been Zuned and Apple's TV will be zuned if it is merely a "me, too" HDTV.
It was foreseen with Microsoft's failed Zune experiment. And this was as much as admitted by the man Microsoft tasked to make Zune go after the iPod. Robbie Bach essentially said it was chasing the iPod with a product that wasn't offering anything new in ways that could get people to abandon Apple's music player.
This is the same thing that is happening to Google TV. I don't have to buy a $300 Logitech device when a $50 Roku will do. Nor will "Google TV" HDTV, with a premium in the hundreds, entice me to buy it when, again, a $50 Roku will do.
That said, I am still not sure that Apple's rumored HDTV will be just another TV. Because Bach, after the Zune failure, now realized there is no point in making and releasing a new product that isn't better than what's on the market. (This is why Apple is unlikely to release an HDTV even if it's iOS-powered).
For Google, it's time they stop the nonsense with anything other than Android. That is where their future is going to be and Google has to go after the television with its core services that are popular and easy to use. For instance, Google+ has a future role that is vastly different from what other competing services offer. A more social entertainment service with pics and videos, both instantly available from users, amateurs, and professionals. Would it be interesting to be able to participate in Hangouts on your TV?
So, if Apple releases just an HDTV with a built in Apple TV and Google sticks with what it has, both products will be zuned in no time.