If you haven't been paying attention, please read very carefully: Akira Yamaoka is confirmed as the musical director for the film and is going to compose all new music to fit this media. Yes, that means you won't have to wait until Silent Hill 5 to hear more of Akira Yamaoka's work. The music you heard in the introduction was simply a montage of Yamaoka's works that were simply substitutes until the first real trailer, which will more likely contain the new, original music.
I actually was aware of that, but it was still exciting to hear Yamaoka work in the trailer, even if it isn't original.