According to some recent comments made by Final Fantasy X scenario writer Kazushige Nojima, a third installment in the X saga is possible if there’s enough demand, and that he himself personally wants to see an X-3 made.
“If there’s enough demand, then we may possibly see new developments… I would personally like to see a sequel like X-3,” says Nojima in the Final Fantasy X/X-2 HD Remaster’s Ultimania book.
Technically, Square Enix seems to have a lot on their plate, as they still have fan demand for a Final Fantasy 7 remake or sequel on their shoulders, but it looks like they also have FFX fans to contend with. At least, anything to get them off Lightning’s saga for a while.
Source: Siliconera.com (via Crunchyroll.com)