A series of photos and mockups has been posted via a Chinese forum (and subsequently shared on Reddit and Famiboards) which detail what appear to be either prototypes or mockups for the upcoming Switch Successor. It's important to be absolutely clear on this one; there is no evidence that this is genuine, however the design and the accompanying specs do seem to be reasonably realistic.
The photos and mockups have been shared via social media from the likes of VGC's Andy Robinson and YouTuber 'Aero', however you can view the whole lot, including the photos, over on Reddit:
The design appears to showcase slightly larger, more rounded Joy-Con, with the right one sporting an additional button below the Home button. The attachment rails are also different, suggesting that Nintendo has indeed adopted a magnetic mechanism for the new console. An additional USB slot can be spotted on the top side next to the audio jack, and a couple of interesting extra buttons/triggers can be seen on the back of the Joy-Con, as previously rumored.
As for the specs (which can be viewed via imgur), we're potentially looking at 12GB Ram, HDMI 2.1 support, and 256GB internal storage.
To reiterate, this may all be completely bogus. However, this is likely the most plausible glimpse at Nintendo's upcoming hardware so far. Hopefully we'll get an official announcement soon, because this is all becoming a bit too much, y'know?