As much as new continent would be great, there's still much left to be explored within Eorzea.

I'd like access to Ishgard, to liberate Ala Mhigo, and uncover more about the Circle of Knowing in Sharlayan.
Of course, I'd like to infiltrate the Empire as well.
Not necessarily to fight them on their own turf, but certainly to recon or acquire their Gunblades.

There's a lot to do yet within the known world. There isn't a reason to extend beyond it, yet.