Rock Band 3 will introduce keyboard and vocal harmonies, as well as Pro mode. It will also support the large library of existing Rock Band songs. How will the new features interact with existing songs?
For example, if I have a player that has selected keyboard as their instrument, will it only allow selection of the new songs that include a keyboard track? Are there any songs existing songs (from the base games or DLC) that will have tracks added for the new instruments?