Well I bet this question was on the minds of several gamers, and might even have been sought by many. We already got both versions for several games including Call of Duty Ghosts and Assassin's Creed 4, so would it really be surprising to get a next gen port for GTA 5?
I mean no official news has been announced yet, and maybe even Rockstar is assessing the situation but we all thought at a point that GTA5 might be released for the next gen consoles. A big reason why a lot of us actually still hold on to our current games is also the fact that GTA5 was released on them.
During a recent interview with Lazlow, one the franchise mainstays, he responded to the question about whether gamers would see GTA5 on the next gen consoles. To this he responded with, "[they] haven't announced anything yet" followed by a wink which Lazlow explained was just a momentary reaction to a "seizure."
I mean at a point it is sort of inevitable. The new consoles already have quite a pretty decent userbase which will only increase. It is a matter of time before we will see GTA5 there, so the real question ends up being, when? Check out the interview for yourself from the link below.
Interview with Lazlow - http://youtu.be/IMGEyxu2crg