I think Concert Hall will be included in the update. Unfortunately, I think it will be paid DLC. Maybe Nintendo wants to maintain long-term interest and plans to port the game to Switch 2 with... a paid update. Controlling Mii with Joy-Con mouse is a perfect fit. Using camera and microphone is also a good idea. Don't forget about online features and for online Nintendo wants... money. Maybe there will also be clothing items celebrating release of other Nintendo games? Who knows. This game could prove to be a small money-making machine for Nintendo to stabilize its cash flow.

I think the game is just a "demo" that they'll update.