Also if they bet on gaming, I bet it would be casual gaming. Stuff they already have on their devices and the kind of stuff people play on Facebook and other social networking sites.
That's not the draw though.
Casual gamers already have quite a few choices:
Wii
Kinect
Ipad/pod/phone/Android/Winphone
DS/3DS/PSP/PsVita
PC/Mac/Netbook/Notebook
There is no reason for a consumer to say: "I have to buy that Apple TV because I want to play x game" when they can play the same thing on multiple devices currently which supply the experience rather well.
Granted, I'm by no means suggesting that Apple will
absolutely not go down this route. I just think if they choose to, it won't be fruitful (no pun intended).
The only proven method of moving/selling tens of millions of units into the livingroom is a dedicated games console+ (which these days means much more than the old days of a strictly games machine).
Much like my viewpoint on Nintendo, perhaps they wouldn't need to compete on hardware (specs), but relying on coming up with an innovative interface which is enough to offset the deficiency in hardware spec will not be easy.
I think WiiU will be the first example of failure to repeat the success of Wii's interface over HW theology.
Perhaps Apple has some magic up it's sleeve, but I don't see it.
The perfect endgame IMO of innovative interface is a infinite resolution Kinect with zero latency.
Within that construct, you can do pretty much anything, even without buttons.