Considering how luck based Corsair seems though, wouldn't it be from Ul'dah? From the Platinum Mirage. Doesn't necessarily have to be a shooter in that case, just have that skill set.

Anyways, I think it would be interesting if they did some sort of explosives based job ;x
Since Arcanist is summoner, the Job for the Muskateer could always be that trap based class that people were talking about being in the dats way back.