Those who have the PS3 version will be able to log in to the PS4 FFXIV and vice versa. However the PS4 version will not be out until February 22nd(?)... you wont be able to play the actual PS3 version of FFXIV on PS4 as it is not backwards compatible. If you trade in your PS3 youll be screwed until February when the PS4 beta comes out unless you also bought the PC version, or can borrow another PS3.