Is there a different option? Following certain horrible precedents, could something like WoW: The Musical work out? Imagine Thrall singing an Azerothian, "I dreamed a dream of Horde's gone by!" or Ragnaros reprising some version of Hellfire. All things considered, maybe the music of Warcraft resembles in-universe chants like we saw from the Hobbit movies. Music, sure, but music that makes sense in the theme of the story.
I can't help but hope, though. And if our favorite characters were to bust out into song, what would they sing? What kind of music are you hoping to see in the movie?