I suppose gated community is accurate, although pejorative sounding. However, even most of the modest older two or three story walk up buildings in this city have a lock on the front door so supposedly only residents can go in, so couldn't one call them gated too?
Obviously nicer, newer buildings will not be as affordable, so there will be more segregation by income as to who can become a condo owner or renter in them. I suppose that is the eternal conundrum of housing, as older perhaps smaller run down buildings are replaced by newer, bigger ones, particularly in desirable central locations. Some cities are more restrictive in redevelopment, but that can come with its own problems. The run down buildings can become more run down and the lack of supply can cause rents to go through the roof. Then the owners of the run down buildings make a killing, but may not put much back into maintaining them.
I think perhaps the best solution is to build more affordable housing, rather than stop redevelopment.