For this matter, we'll only include the big 3 - Liberty City, Vice City, and the whole state of San Andreas (including Las Venturas & San Fierro). And we had a choice to go to the airport to visit any of those cities as we please.
How much space do you think that would take up with the current gen consoles? With the amount of space GTA 5 already takes up I'd expect you would need a 1 TB hard drive to install it all and the beefiest PC in the world. Unless newer consoles would come out shortly after a release it'd be easier to install. What're your thoughts on this crazy concept.