Into the Maelstrom IndeedSince the next area is going to be called "Into the Maelstrom" I think it's obvious that we're going to see a lot more of Limsa this patch. This means, among other things:

I think we're going to see more of the Sanguine Sirens and the The Krakens pirate crews. I think their introduction in the Valentine's Day event was entirely intentional as it's intended to point to them and say "here's a flavor of these two. They'll become important soon." These guys (especially the Captains) were actually pretty prominent in the Limsa Lominsa storylines in 1.0, and I would love to see them used more.

I also think, and man am I crossing my fingers here, that we'll see a new class: Musketeer/Gunner. Limsa Lominsa has high tie-ins with double-barreled pistols and the Knights of the Barracudas have them in their employ. Opening up Limsa further seems likely, but I'm starting to get worried that if this was true they'd want to advertise it more. :c

Also a tie in with the Limsa theme is Satasha (Hard Mode). Though I still have no idea how this would work since the storyline as of right now is sketchy.

Finally, in the category of things I'm fairly sure we'll see is Good King Moggle Mog XII (Hard Mode). I think we had our first touch of this and that the newest iteration is going to feature the Moggles more, giving each of them knew skills that may have us change our priorities a bit.

A "doubtful" thought would be the first Ascian introduced in FFXIV: Travanchet
He was highly involved with the plot to have the Sahagin summon Leviathan, but got lost in the transition to 2.0. So, as far as I can tell it would either mean that he will get introduced now if he ever gets introduced at all.