gta 5 wont took so long like gta 4 because in gta 4 the rage engine was first used and invented like that there were many many many bugs thats because gta 4 took so long.In gta 5 rage engine would be better because the basics are given from gta 4.
The game would be ruined for me when:
-The vehicle selection is so small like in gta iv
-Map is only one city
-no nature
One idea for gta 5 is maybe to go with a girlfriend on a hike so only nature no traffic just relax and go for a walk ,
that was also one reason because i bought san andreas "the nature"