A footnote at the end of a press release from Microsoft reveals that the upcoming next-gen console, Xbox One, is to require a set top box in order to watch Live TV.
"At launch, Live TV will require a supported receiver device with HDMI output (sold separately)."
During the presentation of Microsoft's new console there was plenty of emphasis on the entertainment and television side of things, but it seems that in order to access that content gamers will need to shell out for additional equipment.
The fact was also confirmed in a Q&A, that explained the point more explicitly:
Our goal is to enable live TV through Xbox One in every way that it is delivered throughout the world, whether that's television service providers, over the air or over the Internet, or HDMI-in via a set top box (as is the case with many providers in the US). The delivery of TV is complex and we are working through the many technologies and policies around the world to make live TV available where Xbox One is available.