With works like Caroline, or Change, Sweeney Todd and Les Misérables, mostly through-sung but written in a Broadway-ish idiom,”does the old-school definition of opera as ‘drama set to music’ require a fresh look?” Composer Ricky Ian Gordon, who writes in both genres, says, “The lines have become blurred. I feel like both forms are mutating.” But could a theater market, say, Caroline, or Change as an opera?