In the age where rumors and leaks become frequent, the quality of convincing fakes become greater. A YouTube channel by the name of NOATEST #063 showed off the Nintendo Switch interface with many added bells & whistles which appears to be as a legitimate build in a future update provided by Nintendo. They note that this update would be coming in early February. Whether the legitimacy of the leak is real or not is to be seen most likely in the rumored Nintendo Direct on January 11.
The person guides us through the OS showing new apps, custom folders, cloud storage, messaging, chat lobbies as well as custom themes.
There are hints to suggest why this may be fake. Mario Kart 8 Deluxe is shown as a digital downloaded and user “Big_Red_N” on Twitter points out that the game being 6.8 GB would surely show up as memory taken up, yet only 2GB is taken up on the System Memory and less than 3.2 GB on the Micro SD Card, as 12.9 GB remains on the Micro SD Card and the bar depicting how much space has been taken up suggests the card being used has a 16 GB capacity. There is the chance that games could be used as a dummy file during beta testing and if it were indeed a 16 GB sd card that is being used, some of that space will always be dedicated to the sd card itself regardless of what contents are on it. Therefore, the 12.9 may be partial to the sd card and no space is being used by Mario Kart 8 Deluxe at all.
Another thing to take away from this is the YouTube icon shown is outdated. As with all rumors, take them with a grain of pepper (salt is overrated).