It would be great to have some kind of macro-management. Besides the infrastructure. It would probably take a fair amount of innovation and creativity to figure out a workable extent. And/or be able to toggle between the macro and micro in a less demanding way than was with Sim City 4. Like, to use one in the other, you needed to close one, open the other. I suppose that was a good way to be able to keep it separate and unrelated if you wanted. And I suppose there is already, or there was supposed to be a kind of world effect with sims' actions such as gossip although it didn't seem obvious. But what about greater than that, such as taxes, zoning, utilities and resources, supply chain, education and health systems ... water restrictions ... economics affecting the job market and the price of everything ... and the choice to switch it off perhaps, or as an expansion.
I think it would be a little revolutionary, especially if it could be done without blowing out the specs. It doesn't seem it's being done elsewhere.
Having a Sim City 6 along with a The Sims 5 would definitely set it apart from anything anyone else is attempting to come up with, and make it pretty difficult for the others to copy.