It's easy to forget that places that we haven't yet visited are nothing more than collections of references until someone sits down to actually draw it up. We've heard various bits and pieces about Meracydia, sure. But in the words of Emet-Selch, do we really know 'aught of its present state of affairs?' The land bridge to Meracydia was last up during the Fifth Umbral Era, prior to the Flood, so we're talking over 1600 years since we've had proper access. All of the modern city states were built from the ground up in that timeframe. There are plenty of ways that the writing team can explain why we know so little about it. It's quite literally a blank slate if they want it to be. I do hope, as Ryu has suggested previously, that they draw on some FF9 Mist Continent inspirations for it, like the Iifa Tree for Sephirot's people or perhaps even Burmecia.
I think that there's a bit of a risk in getting there too fast, though. I become more interested in a place as more references filter down and there are more unanswered questions about it. If you're just given all the information upfront, it's a bit more difficult to get attached.
Take Corvos as an example. The remarks that Fourchenault made about Locus Amoenus having other names historically is pretty interesting, given its proximity to Dalmasca. And then you have the Unyielding Blade, the Corvosi sword technique that Zenos originally trained in, which perhaps could be a reference to the Divine Knight techniques of the same name that Meliadoul used in FFT. There's also a lot that could tie Southern Ilsabard into a Void story arc, if that's the direction this is going. Perhaps we'll then get more references around the South Sea Isles, leading to some Spira tie-ins. There are plenty of ways that a story like this can grow organically without dropping places on us fully formed. Either way, I'm sure we'll have a lot more information in a few weeks, as 6.4 will likely be the set-up leading into the next expansion announcement.