To be honest, the only GTA games I felt had good soundtracks were the "historical" ones; Vice City and San Andreas. They had some pretty good tunes on their rock stations, and Vice City even had a metal station that was all sorts of awesome. The only way I could see a Dream Theater song popping up in a GTA game would be if they did another game set in the same time frame as San Andreas (1992-ish) in which case there would be the chance of including Pull Me Under. Beyond that, I wouldn't hold my breath.