Ah that's true.
That being said what about if Ishgard is given a GC too? Plus with the armoury system working the way it is at the moment it means we'll be restricted to "ok i can do everything but the GC i joined doesn't reflect that so I'm being forced to specialise in 1 or 2 classes".
They must be putting in some kind of system to switch GC's otherwise the whole thing won't make any sense. O.o'