I think it'll be a good idea to have some more roads opened up in South City. Now that it is possible to draw the whole track, the devs could edit the surfaces of hidden roads to make them driveable.
Same basically. It would be nice to have "new" content in SO, allowing for new configurations, but it's not really at the top of the list. Completely new environments, physics, cars are all more interesting than building on old stuff.