Seek, and you shall find.
I was quite pleased as well
I hope to see him return someday. A novelty box that can be wound up to trigger him being popped out, perhaps. He's actually one of the PvP finishers though, you can preview him in your finishers tab as "Hidden Minstrel Finisher."
I was pleasantly surprised to see it was an option, like it was tailor made for me!
(I secretly hope this is gonna be a mesmer specialization, that will have a focus as a main hand )
I also hope that the next specializations will be based on the most beautiful and sometimes dangerous thing that is the Music.