Will be free at launch, paid services starting this fall. Update: Nintendo's website provides further details on the suite of paid services (including voice chat), and suggests that a Nintendo Account seems to be integral to the feature.
Nintendo's online services were detailed early in tonight's Switch presentation by Tatsumi Kimishima, current president of Nintendo.
Kimishima mentioned that you will be able to invite friends to play online multiplayer using your smartphone, as well as being able to chat with friends and set up play appointments.
Further details from Nintendo's website suggest the paid service will utilize a Smart Phone device app to provide the lobbies, matchmaking, appointments, and even voice chat. Additional features of the paid service will be monthly access to featured NES or SNES titles that Nintendo states will be feature "newly-added online play" and access to exclusive deals on digital software and content.
These services will be free during a trial period that will end this fall. Nintendo will further detail their online services more at a later date.
