Nintendo updated the Switch firmware version to 6.0.0 a few hours ago. (Sept 18th, 2018).

This is a significant update that brings Nintendo Switch online features such as a possibility to upload savegames to the cloud, and share digital games on multiple consoles.

Removed feature: the update calls out that it will not be possible to unlink your Nintendo Account from your Switch user once this update is installed.

The full changelog:

Nintendo Switch Online* features and functionality have been added, including:
Save Data Cloud Backup

User your internet connection to back up game save data for compatible games
Some games are not compatible with Save Data Cloud
To back up save data or download a previous backup, head to System Settings > Data Management > Save Data Cloud Backup

*Nintendo Switch Online membership (sold separately) and Nintendo Account required for online play. Not available in all countries. Internet access required for online features. Save Data Cloud backup available in compatible games. Terms apply. To learn more, click here.

Added the following system functionality
Upload up to four Album screenshots at once on supported social network services

Only one captured video can be uploaded at once

Select from six new Captain Toad icons for your user

To edit your user icon, head to your My Page on the top left of the Home Menu > Profile

Play your digital software and content on non-primary consoles by linking your Nintendo Account

The term “active console” has been renamed “primary console” in Nintendo eShops
Playing software in multiple consoles has certain restrictions

Display of Nintendo Switch News articles will be limited to match the restricted software parental controls setting selections

Please note that the restriction will only apply to News articles distributed after the release of version 6.0.0.

Change the layout of the USB keyboard to the desired language

To change the language, head to the System Settings > System > USB Keyboard

Removed the following system functionality
After installing the system update, it will no longer be possible to unlink your Nintendo Account from your Nintendo Switch user
General system stability improvements to enhance the user’s experience, including:
Compatibility improvements have been made for a controller licensed by Nintendo

Nintendo Switch 6.0.0 and hacks

If your console is hacked/hackable using Fusee Gelee, in theory this upgrade will not impact your possibility to hack the console, but as always, proceed carefully and wait for word from the hackers that everything’s still working as expected. In particular, some people are reporting that this update is slighlty different from the one that was leaked a few weeks ago. It might be better to understand what the differences are before you make a move.

Hacked consoles can update without burning any efuses with the use of ChoixDuJourNX. (See: How the Nintendo Switch prevents downgrading)

source: ylws8bot