Us Against the World
The Race A View From the Too A Ghost Lukas
Lethal Drug / Love in a lethal dose
Tomorrow Until the Water Flows Over
Rescue St Life is Beautiful
Car Kids So Sad
Some of this songs are too old that I don't see them revisiting for a potential release on LP9... Lukas was released by Natalie Inbruglia (Chris gave her the song).
Gosh it's kinda frustrating to know some potential gems are laying around as unreleased demos on the band's studio... WE NEED THEM ALL. One of the most wanted demos is Car Kids, which seems to be a finished song on its own according to the Mylo Xyloto pop-up book. Also, Tomorrow/World Without You seems interesting (GS era).
Every Coldplay album has had a title track (including Viva, which had two of them, and Ghost Stories, though that one was a bonus track), so I don't think it's far-fetched to expect that there's gonna be a song called Music of the Spheres.