I think a well thought out AppleTV would make a great gaming machine. First, Apple is already used to making processors and graphics for double the resolution of a typical HDTV (think Retina iPad resolution). It would only take a little bit more power to also support 4k televisions (please Apple support 4k)! I want an excuse to get an awesome new TV.

). Second, there are already a bunch of great games on the app store...it's just some of them are hindered by having to use a touch screen. Having a platform where you could count on everyone having a (cool) controller would allow developers to go wild. Third, there really isn't a great device that I know of that does music, movies, education, and gaming well...not to mention one that is not massively expensive. Last, even if the games aren't on the level of PS4, they're going to be close enough for most people while at the same time being a TON cheaper!
Also, if the new iPhone is going to support 4k video recording then it would be cool to airplay that to the television via the AppleTV.
I'm also excited about a streaming television service; although it would be nice to have streaming+on-demand for the channels that are part of the "package". I personally think the whole "package" idea is a bunch of crap...you should be able to pick from free channels that you want, then pick cheap paid channels, and then premium channels. Make your own package but for those networks which are small and need ad revenue, make them free and have them show up first or be pre-selected by default.
I'm excited about a new remote because the current one sucks so very bad. It will be nice to be able to search for music/movies using Siri.
I'm really interested to see what interface they come up with. I think if the remote is awesome enough then the interface could be super great. I haven't seen a "smart TV" interface that impresses me yet so I think this area is ripe for Apple domination.
Like some others, I'm excited about the idea of apps to do things aside from games...like an app to stream NAS/TimeCapsule content. Other home kit apps may be neat too. Learning apps for kids. Fitness apps. It's a whole wide world of possibilities out there!
Things I worry about with the new AppleTV:
1. No support for 4k
2. Small amount of built-in memory (16GB is NOT ENOUGH Apple)...especially if apps support 4k resolution.
3. Expensive and limited TV service
4. Confusing or (on the other hand) not exciting UI
Can't wait!!!