Yes it does... Now what content will be available is a different story. You will probably be able to watch 4K Blu Ray 1st before Video Gamesdoes xbox one support 2160p for retail games or xbla games or movies and videos? and what hdmi revision does it use for the in and out slots?
http://gamingbolt.com/major-nelson-on-xbox-one-rrod-issues-warranty-and-4k-gaming“We are really excited about that too. I am sure your audience knows that 4K is the next big thing. Xbox One is a home entertainment system that is built for future. It supports 4K gaming and entertainment. In fact we are shipping an HDMI cable that is 4K rated. So when you get your HDMI cable out of the box it is 4K rated. We are looking forward to bringing 4K capabilities to our consumers in the future, but it depends on the developers,” he added.