Vagrant Story is the only game that hasn't gotten some form of remake or sequel and with the release of Final Fantasy Tactics: The War of the Lions, it seems like it would be logical for it to return. On this idea, the Ivalice Alliance responds: "Vagrant Story was a title that pushed the PS one to its limits. The technical hurdles in porting it to the PSP would be extremely high. Of course, I think it's the next natural candidate for such an update, and there's no denying its extreme popularity overseas."
When asked if the hero, Ashley Riot, could appear in some other Ivalice title, there is a hint of a sequel if you're good at reading between these lines: "Even in Vagrant Story, there's really not that much we learn about Ashley Riot. Without knowing more about him, it would be difficult to include him in another title." We could learn more about him in, say, Vagrant Story 2: The Wanderer. Just an opinion.