Yep. They've been working on the first expansion for a while now. If you google for "FFXIV First Expansion" you'll find some articles. There isn't a ton of detail on it yet. Most of the questions people ask about the expansion get "We can't really talk about that yet" as an answer. Yoshi-P has said that it's going to have as much content as the relaunch itself (2.0, so not as much content as we have now, but still a lot), and we know that it'll include new classes/jobs, but not how many or which ones. Can't remember what else has been definitively said about it.