Promo material says that MSFS 2020 is using Bing maps to accurately generate models for 400 cities, but is using procedural generation for the rest: https://www.youtube.com/watch?v=mnithCa-H5w&t=1m55s
This video shows urban environments, but the buildings seem to be low poly structures. Okay enough for a flight sim, but I doubt it would be pleasing driving simulator where you regularly see these buildings up close.
The fundamental problem is that the buildings aren't procedurally generated - they're discrete models. They're procedurally placed on the map, but it still cycling through a fixed list of buildings. It looks similar to the real world from the sky, but if you were to go down and drive around you'd see the same apartments and stores again and again.