There should be an OST. However I've heard this song being played not only in the trailer but also during Nero's enemy encounters. Since the DMC1 enemy encounters were named 'Dante's Theme' in the DMC1 OST, it wouldn't surprise me if the song in question was named 'Nero's Theme' given the fact that they re-introduced 'Dante's Theme' in a remixed edition during Dante's enemy encounters.