I'm waiting for Musketeer more than Thief and other future Jobs and Classes because I've always enjoied range classes as DD and the ones that use guns the most.

Also, they have been trying to get Musketeer into Final Fantasy 14 since 1.0.

If there is a new class not far from release as part of a Major Patch release update(Major update release not Expansion release because new content can be released as Major Patch updates as well) then it will certainly be Musketeer.

(That Musketeer Guild in Coral Tower really enjoy taunting me with all those Musketeer class NPCs and musketeer Class Symbol next to the Marauder Guild.)