Yes, the out-migration is happening. The NYC Dems think that their coalition will hold together as they redistribute the spoils from confiscatory taxation to their welfare state clients. I think they will be unpleasantly surprised.
On the other hand, most Jewish people in NYC would continue voting for anti-freedom & anti-Israel socialists even if deBlasio encouraged Antifa to maraud through the streets, breaking the glass windows of Jewish-owned businesses.
So true,alas.