Update: Microsoft sent a statement to GameSpot clairifing that Xbox One consoles can be cut off from Xbox Live but are still useable offline:
Original story: Earlier today, we reported that footage of the still unannounced Xbox One remake of Gears of War found its way to the Internet. Today, it looks like Microsoft is taking a stand against this kind of activity and has temporarily bricked the Xbox One consoles of the people who leaked those videos.
Microsoft hired a third-party QA company called VMC Games to help them test the Gears of War Xbox One remake, and it appears the footage came from two people that VMC hired. Their actions, obviously, broke the company's non-disclosure agreement and they have now been removed from that program. Kotaku received an email sent by VMC to its employees explaining the situation and the punishment they and Microsoft decided to give to the testers that leaked the footage:
"The nature of the leak having had occurred through Xbox One, actually also went against the Microsoft EULA, which is agreed upon when creating an Xbox LIVE account, or any other type of Microsoft account. This being said, as per that agreement with the testers in fault, Microsoft also permanently disabled their Xbox LIVE accounts (as well as other suspected accounts present on their Xbox One kits) and temporarily blocked all of their Xbox One privileges – meaning that for a period of time which Microsoft decides on depending on the severity of the offense, their Xbox One is entirely unusable."