i believe i heard that the 4 will be backwards compatable like the 60 gig was when the 3 came out. if so i would get it now. i will look tho and see if i can find that anywhere.
edit- ignore me. neither xboxone or ps4 will be backward compatible. i vote get it for your ps3 then just plug in your ps3 whenever you want to play it.
Yeh they've said no backwards compatible and if I don't sell my PS3 it will most likely never see the light of day once I get PS4. If they come out and say there will be a PS4 version of GTA5 and they will run a deal if you go from PS3 to 4 then I'd get it. I just bought Diablo 3 for PS3 and I got a code in email that lets me get the PS4 version for $10. So I'll just wait a little longer and see.