They've obviously cracked the infinite streaming landscape as I'm amazed at how big this state is without any obvious loading. So I can see that potentially they can just keep adding and adding locations.
However what I'd rather see is adding in more functionality into this state/city around what is already here. Like every major building having a purpose. It always annoys me when I see these intricate structures that are just used for scenery and nothing else. (Going back to the stadium in GTA 3!).
e.g. let me do something with the windfarm, like put the city in darkness or something (btw I've not completed it yet so not sure if that location actually features, just an example off the top of my head).