Here's the thing:
There are folks that had every opportunity to buy but choose not to do. My family grew up in Williamsburg, my father was able to buy the brownstone that my parents for $50,000 back and many of my former neighborhood had that choice but chose to waste their money frivolous stuff. ENY, Brownsville and Canarise are still places places that haven't been gentrify yet but still people don't take advantage of the situation.
Answer this question: How the hell White people are moving into buildings that are HDFC Co-Op where there are income restrictions and the building's boards has to approve them for them to move in? Think about it...
Canarsie is just as hard to transition but for a different reason. Canarsie has serious lack of public transportation. There is only 1 train station which is on Rockaway and Glenwood. I lived in Canarsie until I was 10 in 1990 so I literally did not ride a NYC subway until I was 11. So when I look at subway pictures from the 80's with all the graffiti it looks foreign to me I never saw any of that. No subway = No Gentrification