I have had this idea for a while.
Maybe we could contact and/or work with some of the SimCity 4 developers? They could use their knowledge of the underpinnings of the game to possibly even modify it (they're developers, not end users, so they might not be bound by the EULA), fix bugs, and accelerate development of community addons such as NAM and RHW.
I don't have the resources to do this but this would be an interesting concept to see in action.
Just to be honest with my opinion: I don't think anyone from the Maxisteam would firstly be interested in this, secondly have the time and thirdly want to work on an old game like this while they have all the new projects ahead. Honestly, it would take one of them that has absolutely nothing useful to do. Logical, no?
Fred
You are not the first to have this idea, if only it could come true. But alas, Maxis is for all practical purposes... no more.