A fascinating piece on gentrification at 2blowhards.com points out that research shows that gentrification can actually cause poor people to stay. A good point made:
Freeman and others, such as Duke's Jacob Vigdor (who reached similar conclusions in a study of gentrification in Boston), note that those opposed to gentrification often presume that the poor neighborhoods are stable to begin with, with settled populations. This appears not to be the case, according to our best studies.It seems to be falsely romanticising the poor to assume that they have different desires for movement, that they are somehow more "stable" than those who have more money. Communities are created through the ebb and flow of people moving in and out of areas, with some people remaining constant: while some areas have higher flows than others, I'm not sure this correlates that strongly with income levels.