Thanks to Gematsu for the following information. During an annual call with shareholders, Falcom revealed that they will be releasing the PlayStation 4 version of Ys VIII: Lacrimosa of Dana on May 25, 2017 in Japan. The PlayStation Vita version of the game has been available since July 21.
The PlayStation 4 version of Ys VIII has quite a few enhanced features over the Vita version. It will run at 60 frames per second, features all new actions and an improved control scheme, and enhanced graphics to fully take advantage of the PlayStation 4, including 4K support for the PS4 Pro.
Hopefully now that a firm date for the PlayStation 4 version in Japan exists, we will start to hear rumblings of a localization for one or both of the versions sometime in 2017. Level Down Games will have more on Ys VIII: Lacrimosa of Dana as it becomes available.