Yesterday, I described most of the basic hardware functions of the Nintendo Switch, via five applications Nintendo filed with the United States Patent and Trademark Office. Towards the end of application number 15/178984 is a diagram of a potential head-mounted display for the Nintendo Switch. This would allow the system to support virtual reality.
The description (section 0776 to 0785) paints something like the Samsung Gear VR or Google Daydream View: the Switch would slide into the head-mounted display (HMD) and the system's acceleration and angular velocity sensors would handle tracking the player's head movement in real-time. The description points to the HMD using lenses to fake a wider viewing angle than what would normally be available on the system. The Switch Joy Cons would be held in the player's hands to control the game, and each one retains its own motion sensors.
It's worth noting that this is Nintendo spit-balling at this point. The Switch display is reportedly 720p, which is rather limited even compared to the VR-enabled smartphones that can work with the Gear VR and Google Daydream. Given this, it's not likely this will be a primary push for Nintendo with the Switch. These are potential applications for the system, much like the alternate Joy Con types I mentioned yesterday. Nintendo may or may not pursue these ideas.