FFXII and Revenant Wings already exists in the same continuity as Tactics and Vagrant Story, so I guess those are already sequels of sorts. I wouldn't overly mind another sequel actually, as long as it didn't have any (or very few) reoccurring characters from any of the previous Ivalice games. However, I would say that with what is virtually the departure of Yasumi Matsuno from Square-Enix it's unlikely they'll be any form of follow up at all.