Xbox One will support eight controllers at the same time wirelessly, but this doesn't mean we should expect games to do likewise.
Local multiplayer games have been around quite a long time, ever since the original NES. The capability of local multiplayer games gave us such killer games as Super Spike V'Ball, Bomberman, and even GoldenEye 64. However, just because the console is capable of supporting eight players locally, it doesn't mean we will be getting games that support eight players locally, especially on Xbox One.
The PlayStation 3 supported seven players wirelessly as well, but very few of its games did, most of which were sports titles.
The Xbox One might even hide the eight player capability behind the Xbox Live Gold paywall, much like the PlayStation 4 is doing with its multiplayer capabilities. Microsoft is known to be that way, keeping its online multiplayer modes locked behind the same paywall much like the rest of its online capabilities except for buying and downloading games and DLC.
On the other hand, Xbox One's ability to use eight controllers could also open up a new way to play sports games as everybody in the room controls one player in a football team, but don't count on it. After all, fitting eight people on one couch is a strain all by itself in more ways than one. Also think about the way the screen would need to accommodate eight people at once (unless the console supports multiple TVs), and you'll notice that you would need a massive TV to begin with just to make it work.
Xbox One will support up to eight controllers - http://t.co/c6k12ROyaH
— Engadget (@engadget) September 3, 2013
The Xbox One eight controller capability could be just an option for the pipe dreams of more ambitious developers, though the possibilities are certainly exciting to consider. Also imagine the facial recognition challenges the console would have to deal with on that level.
In the end, the Xbox One's ability to use eight controllers wirelessly brings to mind the classic Jurassic Park statement that just because you can, it doesn't mean you should.