You Can't Back Up Or Move Switch Save Files
The rumors are true. The Nintendo Switch won't let you backup your games' save files. That means that if you've already put a few dozen hours into The Legend of Zelda: Breath of the Wild—and given how good the game is, we wouldn't blame you—you only have one solution if you think that your Switch is going to break down: pray that it doesn't.
As discovered by Polygon, the Switch stores game saves in its internal memory, and doesn't offer any way to move those files to a microSD card for safekeeping. While the Switch's user interface does have a section for "managing" game saves, once you open it, the only actual option you have is deleting the files entirely—which is fine if you want to start the game over (or desperately need more storage space), but isn't really that useful for anything else. Unlike the PlayStation 4 or Xbox One, Nintendo's online network doesn't support saving files into the cloud.
As a result, you won't be able to take your save files to a friend's house, and if your console fails, you'll lose all of your progress. Previous Nintendo systems, including the Wii and the Wii U, supported SD card-based save backups, and it's not clear why Nintendo removed that feature on its newest console. A Nintendo representative confirmed that "at this time, it is not possible to transfer save data from one Nintendo Switch system to another."
In addition, Polygon says that if a microSD card is inserted into the Switch, eShop purchases will automatically download to the card, not the system's internal flash drive. Currently, there's no way to change that. However, screenshot data can be moved freely between the microSD card and the Switch's internal storage.
Given that some early adopters are running into blue and orange "screens of death" on their new consoles, the lack of save backups (especially for long and involved games like Breath of the Wild) is concerning, and is one area where Nintendo's cool new console comes up short compared to its competition, the PlayStation 4 and Xbox One.