From what I heard it'll be available for ps4. If you have the ps3 disc you will be able to put your disc in and download a digital version for the ps4 for $10. I'm not sure if this is legit just some information to get you started if you're looking around
GTA V for PS4 hasn't been confirmed so noone knows official, however the signs are there that it will most likely be coming to the PS4 at one point or another.