The long-awaited Nintendo Switch Online is coming September
https://www.cnet.com/news/we-finally-know-how-much-nintendos-subscription-service-costs/
The Nintendo Switch online service is launching in 2018, and it'll cost you about $20 a year. (That's US pricing, and converts to around £15 or AU$30). It's the first time Nintendo is charging for online play, but the good news is it's also throwing in a few extras.
Update, Feb. 1, 2018: Eight months after we published this post on June 1, 2017, we now know more specifically when the service will launch: Sep. 2018, a mere seven more months from now.