Harlem has always been a “block by block” deal. That’s much different than, say, Brooklyn or Da Bronx.
I know multiple middle class black families families who have moved into Harlem over the past five years. And these aren’t/weren’t cheap homes. We’ll see how it shapes up for them, but so far so good.
I could tell you stories about Harlem circa 1972-84 that'd curl your hair, make you laugh and/or cry and disbelieve all at the same time.