News from MCV has put FFX/X-2 on PS Vita for the 21st March 2014, well into the end of Q1. This marks the same day that the game is to be released on PS3.
MCV confirms that both games will be in the same package (as expected), and that when buying the physical game for Vita a PS3 download code will be included. The PS3 version will contain both games on disc.