It's a given that neighborhoods, especially in the city, will change over time. The real issue isn't whether people who don't look like the lifelong residents will move in, it's if those new neighbors will treat the area and neighbors with the same reverence and respect that those before them did. I don't think people resent a changing neighborhood so much as they resent people with different values settling down and expecting the neighborhood to bend to their preference.
This is clearly what's at stake in the death of Alex Nieto.