I'd be happy with a keyboard + trackpad that was laid out exactly like the MBP, with the trackpad right below the keyboard, that way my hand has to travel a lot less off the keyboard (I'm a heavy keyboard user). It would have to be wireless, as I want to sit on my couch with it in front of my HDTV that I'll buy someday. I don't care about num-pad and separate buttons for PgUp, PgDn, Home, End, etc. I used to think I would miss them, but after spending enough time on my MBP I don't mind at all and kind of prefer that layout. Basically something like the current Bluetooth keyboard with a trackpad attached on somewhere would be nice.
I like the above idea the best. Extend out the front of the keyboard to make a wrist rest like the MBP, and with the multitouch trackpad located in the same area.
1. Easy to reach with either hand.
2. You know where it's at without talking your eyes off the screen
3. Is located within your peripheral vision, even if you are wearing glasses.
4. It's an ergonomically superior location to being off to one side where the hand must leave the keyboard and they eyes leave the screen.
5. It solves one of the key risk management issues with mice in a normal work station.
6. It allows the user to pull the keyboard into his/her lap and work in a relaxed position (much like with a notebook)
7. The keyboard could also be offered in a split version for even better ergonomics, the resulting extra space used for a larger multi-touch trackpad and two short wrist rests could be added via a re-attachable adhesive to up the ergonomic quotient even more.
8. Mice still could be optionally used with this solution, although I suppose it would be more of a weaning off option than really necessary.
I remember the arguments against mice when they were first offered:
1. "It's not work efficient to remove your hands from the keyboard."
2. "A mouse will cause you to look away from the CRT."
3. "There's no room beside the keyboard for a mouse so it will be located up on the desktop and cause over-extension to reach it."
4. "When you properly tilt a keyboard platform for maximum comfort, the mouse wants to fall onto the floor."
Those who may be against a trackpad, maybe overlooking the advantage of one with multitouch gesturing built in for many often used common needs. This should not be considered an "end-all" for devices. Gamers, Graphic Artists, and others may need additional input devices. But I think you will find that for most application the below-the-space-bar multitouch trackpad is a superior solution.