[Update: Nintendo has confirmed that DS games will still work, and to not expect an international release anytime in 2014.]
Nintendo has revealed yet another 3DS unit -- the "New Nintendo 3DS." It'll feature bigger screens, colored face buttons, a second stick (a tiny nub called the "C-stick," modeled after the GameCube), faster download speeds, a better browser, extra shoulder buttons, and amiibo functionality (NFC). The Nintendo Direct showed off the second stick with Monster Hunter, with the player manipulating the camera with the right nub.
Another bit of functionality Nintendo has shown is enhanced 3D. When viewing 3D effects on the side on a regular 3DS or XL, it'll become blurry. But on the "New 3DS" it'll be very clear regardless of the direction. Look at the gallery below for a visual representation of this concept.
It'll come in white, metallic blue, black, and metallic black, and will be available in both regular and "XL" sizes. It's coming on October 11th for 16,000 and 18,800 yen (for regular and XL respectively).
Right now it's just announced for Japan, but stay tuned.