Is this not what Halo fans talk about Cod doing? ^
Bringing back music from 2 and 3 for Halo 5!? Disaster that is worse than Cod. No, Halo 5 needs to be a new soundtrack, it is no longer the Halo trilogy it is the Reclaimer saga or trilogy, MS make up your mind. New themes, new characters, new weapons, new enemy's, new story, new soundtrack etc.
Besides Halo 5 is supposed to be the darkest Halo in the Reclaimer saga/trilogy. The music must fit that.