I say concepts if you want to add your own, but I mainly wanted to share mine.
If Nintendo were to keep the name N5 for the system, then I though a focus on the "fifth dimension" would be an interesting idea (the fifth dimension being Nintendo/fun/gaming). The following commercial came to mind one day:
The screen starts out just plain white. After a few seconds, a point appears, a simple black dot. Another short moment, then two lines begin to extend out from the line in seperate directions (1st dimension). After it reaches a certain distance they both make 90 upward angles, travel for the same distance, turn 90 degrees inward and meet to create a square (2nd). The square then does a weird split thing (that I can't really explain; best I can do is say that it forms into two squares, rotating toward each other and leaving lines in their wake, making the cube), thus forming into a cube (3rd). The cube then becomes the color/texture of igneous rock and proceeds to go through a process of changing forms (example: rock to dirt to stone to wood to iron to shiny steel, etc.) to represent the passage of time (4th). The screen would then flash, or perhaps the cube would explode, and a message (written or spoken or both) says: "What's the fifth dimension?" Then the Nintendo logo fades in and out in a shadowy sort of way and someone whispers "N5, the next generation of fun", or something along those lines. I made that last line up offhand. Anyway, I thought that was a cool idea. Comments?
There may also be other details, perhaps the line/square part would have a geometric graph layout behind it or something, and maybe the N5 logo would be at the end. But that's basically it.