Gentrification is a widespread phenomenon around the world: old and neglected neighborhoods in potentially good locations are discovered by middle and upper class hipsters, people which have a good sense for design and a smart reading of the urban future. Those people start to move in.
Being aware of their rights, they demand the municipality to improve the roads, pavements, education and personal safety. The neighborhood starts to look good. More like-minded people are moving in. Real estate entrepreneurs follow and the prices begin to rise...
Older tenants cannot afford the increasing rental and leave. Then, the owners receive buying proposals to which they cannot refuse. 
The neighborhood changes its face and its characteristics. 
There are paradoxes in gentrification. One of the is that the authenticity of the place is gone, as the people who created it are had to leave.
And there's the aspect if social justice: people who lived in the neighborhood for many years, cannot afford to stay in their houses.
Does it have to be that way? - In many cities around the world, municipalities find ways to secure the living of the existing population or at least parts of it.
In Jaffa, a suburb of Tel Aviv by the beach, it wasn't solved, according to this film. To make things even more complicated, the issue has also become a matter of nationality.