I think that the story will expand into the Little Almigho (spelling) and us going back to push the invasion back and return the refugees back to their homeland. This was kind of hinted at in the story-line. While they could open Ishgard, I think this would be opened maybe right before the release (relatively speaking) that will lead into the xpac. Though I could see thief being released with the whole idea of a counter insurgent culture in occupied territory, sniper/musketeer works too with the idea of Garlean resistance. Then with the opening of Ishgard, access to the DRK class/job. Maybe the lore behind the DRK will be that there are a specialized group of warriors that must be distinguished enough to be invited to the ranks. It just seems Ishgard should be more of an xpac vs a simple content update