I took a little relaxation time out of my busy schedule to put this together last night. I just took components from one of my previous efforts and put together something that seems fairly reasonable. (Ah! the beauty of cut-and-paste).
Nintendo probably don’t want to change the design too much or introduce new functionality (such as an analog stick) because the platform is fairly well established. I doubt that they will drop the Gameboy Advance game slot because it may be used for add-on cartridges (such as the rumble pack).
With the success of the Gameboy Micro and competition from the (fairly large) PSP, they probably want it to be smaller, cooler looking, and somewhat customisable. A faceplate is probably a good idea so that they don’t have to keep making different colours later in the lifespan of the product. It will probably still look fairly sturdy because they don’t want it to break easily.
So here it is. The screens are the same size, but everything else is smaller.
Note: I still like the ipod style redesign better!