I don't think that it's likely for us to see the New World anytime soon. In terms of landmasses that we're aware of, the two major continents that we are yet to see are Meracydia and the New World, and each one easily could have its own multiple-expansion story arc around it. And between the two, not only does Meracydia have more plotlines available to draw from at the moment (like the Warring Triad, Allag, and Azadja), the Void storyline itself seems to be gearing in that direction ultimately. But that's not a single expansion deal. Meracydia has been mostly cut off from Eorzea since the time of the last ice age (Age of Endless Frost - Fifth Umbral/Astral). So it's likely not all that easy to get to (dangerous seas/winds, etc), and there'll probably be stop overs along the way (South Sea Isles). It shouldn't be hard for them to get at least three to five expansions out of it, including Meracydia itself.

The same is true for the New World, although I expect that we'll hit Aerslaent enroute through the Northern Empty.

I'm hoping that at least one of these continents has a more futuristic/steampunk leaning to it rather than classical fantasy, just to mix things up.