Well at least the DS has four face buttons on it, so you could have an easier time playing it than other music games.
Maybe you could use the stylus to draw the characters/costume details? I donno.
Anyway, I'd consider it improbable (especially since DDR development is dead on the arcade front) but since DDR GBA happened I wouldn't declare it as "never" at this point. Wouldn't hold my breath, though.