Considering that alot of the stuff these first patches are adding is stuff that was talked about being in the game even durring beta(but either didn't make it due to time or because it just wasn't important enough to get that in yet.) I could easily see this type of class being added in a patch.
Then remember that Musketeer has been "on the roster" of classes we were supposed to have received even way back in 1.0. So, adding a class/job like that (which would also finally give Limsa 3 classes like the rest of the City-states) I could easily seem them sneaking it in an update since there isn't really any super secret Lore behind getting it into the game, it already is(we just can't have it as a player yet because of mechanics, not lore).
Other things like Samurai/Ninja/Dark Knight/ etc. would require a new set of lore behind why we haven't seen anyone wielding it yet, maybe even a whole new region of Hydaelyn to explore. I can see needing an expansion for big updates to lore like that, but for something that is all around us already(especially in Limsa) I don't see them needing to wait for an expansion to throw that bone to us.
Then remember that Musketeer has been "on the roster" of classes we were supposed to have received even way back in 1.0. So, adding a class/job like that (which would also finally give Limsa 3 classes like the rest of the City-states) I could easily seem them sneaking it in an update since there isn't really any super secret Lore behind getting it into the game, it already is(we just can't have it as a player yet because of mechanics, not lore).
Other things like Samurai/Ninja/Dark Knight/ etc. would require a new set of lore behind why we haven't seen anyone wielding it yet, maybe even a whole new region of Hydaelyn to explore. I can see needing an expansion for big updates to lore like that, but for something that is all around us already(especially in Limsa) I don't see them needing to wait for an expansion to throw that bone to us.