I bet they'll rework older songs to fit in with the new stuff. I'm hoping for a couple Reanimation tracks like P5ng and 1 Stp Klsr. That would be pretty epic. Also, with how Mike's singing more, I'd like to see No Roads Left.
As for the actual A Thousand Suns tracks, they better release Iridescent as a single so that they can get thousands of people singing that choir part in there. I also can't wait to hear how Mike sounds live since he's doing a lot of singing on this album.