For Manhattan I don't doubt you and I would say Paris is in the same boat. I look at DC and I think there is more flexibility, same for Rome. I don't know L.A. but I've heard it called a giant highway system with houses around it.
Some dense urban areas can't help but remain what they are, some may not.
Good point about telework and its possible consequences re. other urban commerces.
As to disinfecting mass transit, I wonder if that's going to make authorities much less tolerant of graffiti and the like (i.e. much less tolerant of folks messing with what they just cleaned up).
Anyway, there's no way to know right now, but it's amusing to speculate.