Games from the last generation getting ported to the current generation is a common practice, and there's a possibility that Square Enix will be continuing that soon. Recently a listing for an Xbox One version of Final Fantasy XIII was discovered on the Xbox Store.
Originally discovered by XboxAchievements.com, a (now taken down) Xbox store page that featured Final Fantasy XIII was found. Notably the page appears to be a Chinese page, as evident by the Chinese in the URL. While the page did not specify if this was a port or an updated version, it did feature some new box-art that at least proves it is likely a new release and not just an addition to the Xbox One's backwards compatibility list.
There is also a chance this may just be a Chinese page for a streamable version of the game. Back in April Square Enix announced they were partnering with streaming company Ubitus to bring a streaming service to Xbox One consoles in China. At the time the service went into beta and the only game available for it was Final Fantasy XIII. This could be a listen for the full game when the service launches. This wouldn't be the first time Ubitus is being used to stream Final Fantasy XIII, as Square Enix has also used the service to stream the game in Japan over Chromecast.
Final Fantasy XIII originally released in 2010 in the United States on both the PlayStation 3 and Xbox 360, and four years later on Steam. The game was originally well received by critics, but not very well by fans and has since gone on to be remembered as one of the low-points for the series. It was followed up by the 2012 sequel Final Fantasy XIII-2, and the 2014 Lightning Returns: Final Fantasy XIII. There is no word on if either of the sequels will be getting ports, or if any of the ports will be coming to the PlayStation 4.
Final Fantasy XIII is currently available on PlayStation 3, Xbox 360, and on Steam if you don't feel like waiting.