The 13th just seems like something that's much in the writing team's back pocket for them to just immediately pull it out. I can't see anything directly happening with that for a few years out. I also don't wanna rule out going to places within Eorzea itself because there are still a number of places that exist but aren't actually accessible in the current game in any form (like the Coerthan Lowlands, O'Ghomorro, or Southern Mor Dhona).