With the adding of notebook/journal thing, it would be amazing if there was a placeable sheet music paper, which you would place in front or onto your instrument, that you could click e on and edit, writing in your own sheet music, or copy pasting sheet music from the web, and being able to view it while using the piano, without needing to do some weird windowed mode thing.
You could also have multiple sheet music papers that you could pull out and place on instruments, which your friends could see as well when they play the instruments in your condo.
I believe I remember Mac stating a while back that he wanted to do something more interactive with sheet music. Something like DDR, where the notes fall towards the keys you need to press. It has been a while though, so I don’t know what the current plan is. I’m certain some sheet music system will be implemented, though!