The latest issue of Japanese magazine Nintendo Dream has a feature on the Switch, and as part of it they asked Nintendo a few questions about the system. One of which was about the name:
|“We decided that this name would be the best fit for our product for two reasons. It represents one of the defining features of the Switch, the ability to seamlessly ‘switch’ between the TV screen and Switch’s screen, while also embodying the idea of being a ‘switch’ that will flip, and change the way people experience entertainment in their daily lives.”|
A few more details can be found at Nintendo Everything via the link below.