You wanna see a really interesting case of gentrification? Check out this scene from Blues Brothers:
https://www.youtube.com/watch?v=nUUyFrHERpU
At the 35 second mark, you can see the addresses of the businesses. Check it out on Google maps today. The buildings have been razed and the street has been “gentrified”:
If you want a really interesting case of de-gentrification, look at any older neighborhood in Northern Virginia. They all start out pretty nice and then turn to crap as they age.