Nintendo Switch Online launches this September with save data cloud backup and 20 NES games with added online functionality!
More info here: https://www.nintendo.com/switch/online-service/
Details of the cloud save feature will be announced at a later date. Beyond the initial 20, more NES games will be released.
Also, here's the 10 revealed NES games (the rest will be announced before the Sept release):
SoccerBalloon Fight
Tennis
Ice Climber
Donkey Kong
Dr. Mario
Mario Bros
Legend of Zelda
Super Mario Bros
Super Mario Bros 3
Last edited by Ultravolt - on 07 May 2018