Then why are there discussions on gentrification. There are reasons why individuals are moving back into the city, especially the up and coming class of individuals. The new comers to the city are fighting urban sprawl by making the move.
It's a small minority. Even more interesting, while gentrification is arguably the solution/balancing phenomena to this problem, it's generally speaking a term with a negative connotation associated with it.
Only because most US cities do a piss poor job of providing housing support for the poor. That's a failure of policy, not gentrification itself.