To be more serious though, I do feel that Meracydia is a real contender. While the continent was devastated in the time of the Allagans the continent has since been healing and it has been mentioned a few times (like in the Encyclopedia Eorzea) that there are colonies or tribes or some form of inhabitants in areas. We are also still missing 2 sons of Midgardsormr and I personally would really like to continue the First Broods story. There are also so many races in reference to Meracydia that we learned about on Azys Lla that are not of the brood (i.e. Sephirot's tree people race and the race that revered Sophie) that I am dying to learn more lore about. Meracydia has ALOT of potential besides just being regarded as a spent continent. Sharlayan is also plausible, though less exciting for me personally and I do believe they are going to put Garlemald to bed, at least for now, before the next expac. I can see them coming back in the future in need of assistance kind of like Ishgard though. I dont know. Meracydia is what I am wanting but who knows whats going to happen.