When the Xbox 360 and PS3 launched, the world was just making the transition to high definition TV sets. There were growing pains, and the feeling that it'd be years until enough people owned one that they would become mandatory. Guess that time is now.
While the Wii U - and let's be real, it's basically last-gen tech - soldiers on with component output, both the Xbox One and PlayStation 4 will only output video signals via HDMI. The Xbox One specifically states that it needs a "720p or higher HDMI-compatible TV", while the PS4's spec sheet says the console only outputs via HDMI.