I should say that my post was, as always just my opinion.
But thats all we have anymore!
If they did add a city expansion, it would be cool if it was physically connected to Liberty City.. Seems that might make more sense, if it was possible.
I hope the next full installment, (the equivalent of VC) is GTA (IV) London.
Then the equivalent of SA could be Japan.
I'm just rambling at this point.