This problem is already leaking into the world of physical consoles. Afaik the only (legal) way to backup your savegame data on a Nintendo Switch is to transfer

This problem is already leaking into the world of physical consoles. Afaik the only (legal) way to backup your savegame data on a Nintendo Switch is to transfer it directly to another Switch (and deleting it from the first) or get an online account (which was only available 1,5 years after the Switch launched). No saves can be stored on cartridges or the SD card. So if your Switch goes broken for some reason and you didn't want to pay for online backups every month your out of luck.