[Update] We now have even more evidence that a black 3DS XL will be headed to North America. In a commercial for Mario & Luigi: Dream Team, which is currently airing on Cartoon Network in North America, the game is being played on an all-black device.
Here's a shot taken from the commercial (via IGN):
While this hardly confirms anything, you may recall that the yellow Pikachu version appeared in a commercial just before it was announced, so this wouldn't be the first time Nintendo pulled a stunt like this.
[Original] It appears that Nintendo may be offering an all-black model of the 3DS XL to consumers in North America, as GoNintendo has discovered a Canadian flyer that suggests this new color option will be made available this Friday.