GTA should come home. They should do a GTA Great Britain or even UK. The geography would make for a great map. All the urburn areas are kind of south and central and the forestry is north near Scotland so it wouldn't be like San Andreas where you are constantly having to plough through countryside and lakes.
People who want GTA set outside of the US fail to see that the entire premise of the game is a parody of American popular culture. It's an exaggerated parody of America mainly through the perspective of the Brits who have written every GTA since the beginning.
I would love to run around causing chaos and destruction in a fictionalized version of London... Or any other world city.... But it ain't gonna happen with GTA.