UPDATED with new mock-ups below!

Done by Chris Ro on NeoGaf, for people having problems visualizing it maybe this gives a better idea. I personally think the screen will be more in the 6-8 inch range though. 

EDIT: Here are some new ones, 

This one is from Twitter, don't know the exact source, but I saw it on NeoGaf:

DS/3DS backwards comp/or Virtual Handheld!

This next one is from Reddit:

https://m.reddit.com/r/NintendoNX/comments/4xb2qq/the_point_of_removable_controllers/?utm_source=mweb_redirect&compact=true

That is soooo Nintendo-ey, could totally see them doing something like the above, swappable controller wings could come bundled with different games. 

Looks interesting, cant wait for Nintendo to actually unveil NX.

gotta admit, this is very strange.

If Nintendo has a device like the above that can run Android apps too ... I think it will do quite well (or better) depending on how they execute it, but I'd personally rather buy that than a $400 16GB iPad Mini.

I like the detachable controllers cause it's a better version of my case idea.

When you want to play games, have the controllers on but when you want to carry it around as more of an elegant looking device, you can do that too. Of course, it also has the benefit of plugging into your tv and etc which is also great.

The controllers and its ergonomics while being detached is gonna be my main concern. Is this gonna be another wiimote/numchuck thing cause how am I supposed to player shooters in this thing when its connected to the tv. Oh and no, that doesn't make it a hybrid.

Edit: Oh and the pricing too is my other issue

Shooters on the Wii were fine control wise. 

Though I'm sure Nintendo will offer a standard "Pro Controller" for those who want it. No big deal. 

Gives the supposed concept a much clearer image, looking at that tbh I think something like that can work well.

Shooters on the Wii were actually really good, on the actual device here it basically is like a gamepad that the sides where the buttons are can detach from, it would play any game just fine.

Sitting in the airport yesterday a pair of kids next to me were playing a FPS on an iPad with no buttons just fine, lol, this will be a huge upgrade on that kind of experience.

woa! and it suddenly looks like something that could actually work, good job from the designer

official NX presentation will be really interesting