You can see the success of this "plan" in Boston by looking at new Census data. Go to this map and click on various census tracts; you can see that the white population in the South End, Roxbury, and Mission Hill (all near the Orange Line) has increased over the past decade while the number of African-Americans has declined or been stagnant. Then go to this map and click on tracts in Everett, Malden, and Revere; the black population has soared while whites have gone elsewhere.
This isn't really a conspiracy, of course. It's just a matter of higher-income groups rediscovering the advantages of living in the heart of the city (now that crime has gone down and pizza shops have been replaced by cocktail bars). The question is what will happen to inner-ring suburbs as their relatively low housing costs attract more and more immigrants and low-income residents. They're likely to become more dependent on state aid in order to provide education and other public services. My fear is that they will face a political alliance between prosperous Boston and well-off suburbs (all of them able to generate income from high property taxes and lucrative commercial property) that will impose "fiscal discipline" on less fortunate communities.