When the Wii and Wii U were released, Miis were still popular, suggesting that Nintendo did not seem to want to separate themselves from them at the time. This trend continues with the Switch.
During an interview with Kotaku, Nintendo confirmed that the Switch will indeed feature Mii support. However, they will be buried in settings, but still offer more options for customization.
The full Nintendo statement can be read below:
There is a Mii Maker on Nintendo Switch. The software to create Mii characters is now located in System Settings, and no longer resides on the HOME menu as a standalone application. You can also create a Mii character from the Profile screen. Making Mii characters is similar to the method used on past systems.