The nearest miss is the dual-card DSi, apparently rejected for being a little too fat. Also shown was a 1998 Game Boy Advance SP touchscreen "concept" which never made it past the "let's bolt a touchscreen on and see what happens" phase.
The most interesting not-quite in the whole presentation is the lard-assed Game Boy Advance predecessor from 1995, which was shelved for terrible performance and, well, the fatness. That's a DS next to it, in case you were wondering. Check out the full story at [Kotaku]