I really, really hope it doesn't take place in a single city. It's not just about different stuff to do, customization, etc. What was really awesome about San Andreas to me was having so many different environments. You see a mountain far away and you're like 'I'm gonna try go up the mountain on my bicycle and jump on parachute!'. I love the feeling of driving from one city to another through highways, seeing forests, deserts, mountains... Being able to go to little towns in between cities, etc.
The feeling that you are in this huge state (and SA wasn't that huge when you think of some games these days) with so much freedom... no matter how fun and varied it is, having it in a single city can't be as good for me.
No troll is too much for me to handle. I rehabilitate trolls, I train people. I am the Troll Whisperer.