Yeah, just from the presentation they did, I thought it might just be for the app features as well since they were pretty vague about it. Saw the section about the online service on their website though and checked that which confirmed it wasn't just for the app. I honestly wasn't expecting it...
http://www.nintendo.com/switch/online-service/
It's not just a smartphone app. "This service lets Nintendo Switch owners enjoy online multiplayer gaming as well as a dedicated smartphone app that connects to your Nintendo Switch system and helps you connect with friends for online play...