Grand Theft Auto 5? we proberly won't se that untill the next generation.
Because you have got to remember...
GTA 1 ---> GTA London 1961 & 1969 (PS/PC)
GTA 2 (PS/PC)
GTA 3 ---> GTA Vice city, GTA San Andreas ---> GTA Advance, GTA Liberty City stories, GTA Vice City stories. (PS2/Xbox/PC)
GTA 4 ---> GTA (City name), GTA (city name) ect. (PS3/Xbox 360/PC?)
GTA 5... (PS4?/Xbox 720?/PC?...)
So GTA IV in my oppinion will start a whole new cannon of GTA games but for new generation gaming consoles, kind of like GTA 3 did.
So GTA 5 we proberly won't see untill 2015.