I'm sorry, I don't follow your logic. As was presented by Jobs, you can use an iPad to stream to an AppleTV. No mention of a computer being needed, just a WiFi network. Perhaps your thinking of the computer replacing the WiFi network in the above...
As soon as you possess one of the new ones, try to set it up without a computer. Try to get it going day 1 without a computer. It may indeed work out that after you do your set up, you can completely turn off the computer and solely use an iDevice to push video & audio to it- we'll know soon enough- but I am extraordinarily confident that the new one will need a computer in the mix. Thus, computer +

TV + iDevice if you want to airplay, or maybe a laptop can airplay with an

TV, which is the only way I see it being just a computer and an

TV for airplay, no iDevice required. I don't see any scenario where it will be able to be just an iDevice and an

TV.
Besides, even if that would work out, as soon as the iDevice goes out with you, the device would then become useless for your own household content at home for the rest of the family, until you bring the keeper of your content back home. Again, a computer is pretty much a required element for the new

TV. Airplay just cleverly motivates iDevice hardware to join the twosome that has worked well for the last 4 years.
Who said the AirTunes functionality went away when it was renamed? You want to stream music? Fine. You want to stream videos now? Its like magic. AirPlay is AirTunes + Video + stream from iDevice.
Airtunes means no iDevice required. If you're having a party, you don't want your iDevice laying around pumping audio or video to your

TV. That would be a great way for your iDevice to disappear. It's a lot harder to smuggle an iMac or Mac Pro out of the house.
Airplay is cool, no doubt about it. And it would be very cool to transport your content to someone else's house on an iDevice and be able to push it to their

TV. Very cool.
One of the things I didn't do with the original

TV was sync content to it. Guess what? I waste power. My iMac is on 24/7. Does it go to sleep? Yes. Would my

TV wake it up when it was going to play stuff from it? Yes. Why no syncing? It took forever to sync stuff, even over wireless N. I have more than 150GB of TV shows/Movies in my iTunes. Mostly in 720p. All played fine over the network.
That's great. But like all such comments, YOU and YOUR tastes/needs are not representative of EVERYONE ELSES tastes & needs. I have about 280GB of content that I choose to sync to my

TV, and another larger cache that I stream. I prefer that setup to streaming everything for various reasons.
Your way works for you? Great! My way works for me. That should be equally great. Your way should not be forced on everyone else just because it works for you.
And you do realize that you could have set up your

TV, then used a temporary wired connection to sync all that content quickly, then switched back to your wireless set up, right? Very easy to do that. Then, you could completely turn off your Mac, save that power, and still have access to all of your content on demand. I just did this very thing for one of my family. We couldn't run a network cable to where their TV was located, so we set it up via Wireless N, then unhooked the Apple TV and brought it to the computer + router, cat 5 cable connection, iTunes sync. The sync went a lot faster than wireless. When it was finished, unhooked it from the cat 5 cable, took it back to the TV, and now they have lots of key content synced to the Apple TV, with the rest available to stream via wireless from the Mac. Easy and Fast.