How will legacy music game controllers that do not have solo buttons function with the new Freestyle Guitar Solos feature?

Rock Band 4 will support 5-button guitars, including Freestyle Guitar Solo functionality! Because these guitars do not operate with solo buttons, the types of sounds you can create will be limited. However, the game will be able to fully recognize the guitar’s limitations and will never give you unachievable prompts during the Freestyle Guitar Solo sections. You will be scored in the same manner as those who are able to use a 10-button guitar for Freestyle Guitar Solos. Simply put, you will be able to play Freestyle Guitar Solos to the full extent that it can be played on the 5 main buttons of the guitar.