The Xbox One X will clearly be a more significant upgrade for a 4K television owner but, as it so happens, many of the interested customers don't necessarily own one yet. Microsoft has therefore made an effort to also provide the 1080p experience with extra bells and whistles, and that primarily happens through a technology referred to as supersampling.
This process should give games being played on the Xbox One X a graphical advantage, even if it's running on a regular HD screen, however, it has yet to be properly demonstrated to the public, but Microsoft is committed to doing that ahead of the launch in November.
Recently, Aaron Greenberg confirmed via Twitter that a demonstration will happen before the launch, so all we need now is a date for this presentation. Have you been concerned about the benefits the console will bring for non-4K users?