You gut the integration, you lose the accommodation. Integration = demand. Accommodation = supply. Cause and effect. As I point out in mySpace Syntax of downtown Dallas post, the real estate market and building technologies built upwards at the exact same time as cities, states, and federal government unwittingly conspired to undermine the demand to fill those towers. But since the towers were new and shiny with whatever modern doo-dads a business may look for at the time, they cannibalized from historic buildings...which could then be torn down for parking all the residents that fled when their homes were taken for highways.
So I did a quick exercise examing inner loop highways in various cities, all at roughly the same scale. When given the time, I'll likely add in the railroads, which also have a divisive effect (see: "other side of the tracks") as well as a rough approximation of the land areas which remain relatively vibrant. It might be nice to test what the ratio of vibrant area vs overall land area within the loop might be and if there is any rough correlation.