Bullish, but still credible overall:
Apple TV will accidentally (though less accidentally than in the case of the iPod touch) dominate the console gaming market. The OS update that brings the App Store to the TV will bring Game Center as well. Games will be the top the store’s charts4. More advanced, console-quality games will follow, but the beauty of the situation is that those aren’t even necessary.
Austin Sweeney's assessment isn't far off my own, though I'd be hesitant to go out on a limb and suggest an explicit Apple TV gaming refresh + API as soon as iOS 7 arrives. The APIs for writing sprite-based games just got a massive push, and the Made-For-iPhone controllers will likely take a little while to appear. I'd put my money on seeing a bunch of SpriteKit-based iPod-to-Airplay games with controller support appear first. Add a third-party controller, or just use the iPod/iPhone's touch screen, and you've got a de-facto home console. From there it's a relatively small step to open up iCloud so you can download eligible "TV-playable" games to run right on the (upgraded?) Apple TV.
The usual suspects will whine that this isn't a serious console, and that Apple's curated store policies are anathema to "serious gaming", but most people won't care one jot. As Austin points out, the lack of serious games didn't hurt the Wii one bit, and Nintendo opened up gaming to a whole new audience. Imagine what happens when consoles cost $99, get annual upgrades, and run the games you already bought for your phone.