If the N5 uses 5 inch media, yes, dvd compatibilty as a plug in device like the Xbox. If a n5 user needs dvd compatibility, they can spend the $25 on software+licence sold as a remote.
3rd memory card slot, but make it a usb port ad make it capable of dealing with USB mass storage devices. Sure it will give the nintendo licencing structure issue, but it will also make having a built in hard drive a moot point as they'll be easy to buy from any vendor. Nintendo maybe gets to sell a seal of approval to vendors for a buck a pop. This will require an overhaul of the memory card filesystem.
V-Chip. Password set by vendor at point of purchase. Nintendo doesn't want uber-questionable games on their system like GTA3/GTA Vice City, but they need them for image reasons. A V-Chip would require parents to authorize M rated games before the first play, and then disable them later if need be. This forces the responsibilty in the parents laps where it should be and leaves Nintendo free to pimp the system to companies like rockstar without feeling guilty.
Comes with ethernet port, supports optional dial-up modem via serial port (usb? or make it compatible with GC modem?). Have to agree on gamespy. Games should have online capabilities where it makes sense. Mario Party/Mario Kart/Smash Bros/Golf. Pimp the system to MMORPG makers.
More USB Ports. Support of HID mice and keyboards. Require makers of games to focus first on controller, but most FPS just work better with Keyboard/Mouse combo. Also makes buying a keyboard for mmorpgs cheaper.
Games are required to support both progressive scan and 16x9 aspect. 720p and 1080i are optional resolutions, and supported, but not required. Note - once progressive scan is there, interlaced is inherited. Just show only half the lines at a time. Games can also support interlaced modes directly and in some cases enjoy a better framerate.
Backwards compatibilty would be good. Will be easily attainable if nintendo increases clock speed, but keeps backwards compatible cpu/ram/gpu, otherwise cpu/gpu/spu/ram in a reduced number of chips is probabally not far away. Does anyone know how many revisions of gamecube hardware there are yet?
-bmfrosty (more to come)