I would enjoy the trio as long as they weren't just "Ice Climbers except there's three of them."
In their game, you only control the third Chorus Man and you have to mimic the two others. I wonder if that can be adapted to Smash. You could have two AI Chorus Men that, unlike Nana, lead the fight instead of tagging along; and the Chorus Man you control will be extra strong if you can hit in their tempo. They make a beat, you maintain it; sounds simple, but I haven't a clue how practical that would actually be.
As far as the actual moves of the C-men (LOL), Sakurai would have to take some liberties, since they do nothing but stand around and scream.
Anyway, as much as I disbelieve the rumor, I still think they sound like intriguing fighters, so add me to the choir! (I'd be the one that messes up the rhythm and you'll all be peripheral-staring at me in disappointment.)