Earlier today, a YouTuber posted a video claiming that they’d come across a LinkedIN profile of a Namco Bandai Singapore developer that had listed the fact that they were working on an Unannounced Game (First Person Shooter/Adventure Exclusive to Nintendo Switch) as well as Ridge Racer 8 as a Switch exclusive.
Now, this first person shooter/adventure could not be Metroid, but rumours have been swirling since its announcement from known Nintendo insiders that Metroid Prime 4 is being developed by Bandai Namco. 
Whilst the profile of the dev was not posted in the video, I have tracked it down and can confirm that it is a legitimate profile with 20 years experience across of a number of reputable publishers.