While no date has been revealed for Europe yet, Square Enix have announced that the remastered Playstation 4 version of Final Fantasy X and Final Fantasy X-2 will be coming to North America on May 12, and will be available in Japan on May 14.
From the press release:
FINAL FANTASY X/X-2 HD Remaster brings together FINAL FANTASY X and FINAL FANTASY X-2, along with FINAL FANTASY X: Eternal Calm and FINAL FANTASY X-2: LAST MISSION, each originally exclusive to the Japanese market.
Cross-Save Functionality – Players can transfer their save and continue their progress across the PlayStation®4 system, PlayStation®3 system, and the PlayStation®Vita handheld entertainment system. (PlayStation®3 and PlayStation®Vita versions sold separately.)
Ability to Switch Between Original and Remastered Soundtrack – Play FINAL FANTASY X with the beautifully remastered soundtrack or, new to the PlayStation®4 system version, switch back to the original classic tracks.
Remote play – Supported for the Playstation®Vita handheld entertainment system.
Have a look at the graphics comparison below. Each of the pairs are Playstation 3 versus Playstation 4 graphics, in that order.