They should make Google sketchup DSi, not as DSi ware but as game, with a couple of standard colors and furniture to create buildings like houses and offices, I think it will be great with the touch screen.
I am a 3d modeler (hobbyist) and I think I can say that won't work even if they put a ram/processor chip in the cart, as models can get high polygon counts pretty quickly. The concept is nice though.
