Seeing as there's a guild right in the Coral Tower waiting to be occupied by someone, let's just get the speculation out of our systems.
I see Musketeer as a primary class with the storyline centering around our services to the Admiral. Not really sure if Hexaguns would be used (likely if Corsair/Pirate turns out to be the job) or regular pistols.
I cannot see this class or job being a semi-support class in the way COR was in XI unless the devs weave in some Gambler elements better than in XI (i.e. streamline the roll options, make them last long enough to get some shooting in, etc.)