There is widespread speculation about Final Fantasy XIII-2 following the registration of the domain name

The domain, which suggests a direct sequel to FFXIII similar to how X-2 was a sequel to X, was registered by Corporation Service Company, who in the past have registered website domains for Square Enix titles MindJack, Nier and Gun Loco.

Square Enix is holding an event in Japan next week, so hold onto your hats. An announcement might be on the cards.

Via superannuation

Final Fantasy XIII wasn't the blockbuster success Square Enix hoped it would be, but it still has a large fan base who would lap up a direct sequel. Presumably a follow-on title wouldn't take 20 hours to get going.