The Nintendo Switch Online service is scheduled to launch in 2018 at a price of $20 a year. For that price, you'll get instant access to a classic game library and the ability to play games online.
You read that correctly: Nintendo is going to gate access to online gameplay.
After this service launches, you'll need to fork over a subscription fee to play online games on the Nintendo Switch. For the $20 price of entry, though, you'll also gain access to a library of classic games. The only three games announced thus far are "Super Mario Bros. 3," "Dr. Mario," and "Balloon Fight," which are all classic Nintendo Entertainment System (NES) games.
It's unclear when the service will actually launch; Nintendo has only given its service a release window of "2018."
It's also unclear if Nintendo will have a separate "Virtual Console" service, as it has in the past — such a service has traditionally offered a paid library of a la carte classic games. That could very well also be coming in 2018.