I could see a demo disk similar to the E4A demo being distributed to certain store chains. But it is possible that they may decide the game is hyped enough and doesn't need a demo to boost player interest.
Several people I spoke with were skeptical of SMG due to the wiimote nunchuk controls, and after playing it at a kiosk, purchased a copy. But did they really NEED SMG demos to boost public interest? I kinda doubt it.
So the other logical conclusion being that they tauted the hall out of this game for so long they wanted to give the fans a taste of what's coming..that seems actually reasonable.
And on that note, Super Smash Bros. has been one of the most successful gaming franchises Nintendo has ever had. So it makes you wonder if we will see demo kiosks around and after the launch like we have with SMG?