We should have Mor Dhona and Coerthas coming in the launch version of the game as well as West Black Shroud (Anceint Eorzea Stratum), the special battlefield zones for all the primals. They also mentioned in the E3 live letter that although only 40+ zones will be in at launch, they have plans/capacity to implement a LOT more via downloaded updates. Ishgard and its content is supposedly coming sometime between launch and the first expansion and since yoshida mention loosely they hope to have an expansion 1.5 years after launch (They expect that to be delayed) that alone will be a sizable addition.
We might need to wait till sometime after launch to get truly new looking themes/areas and I look forward to what they come up with it as the game expands. One of my favorite part of the MMO is how worlds just keep getting bigger and bigger as the game goes on, usually/hopefully integrating seamless with the original world (I don't expect a Dalamud/cataclysm like event to happen again for this game

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