No, the rich leftwingers will leave, the working folks that can't afford to leave will be the ones left holding the bag.
And they’ll still support Mamdani.
You have to look at the big picture. These socialist big mayors don’t care about their cities, it’s a means to an end. Gain a foothold in all the big cities, then work together, and have the leverage to impose their will on the state, and subsequently Federal government to get Socialism nationwide.
I mean, one cannot have Socialism in one city, and these mayors know it. But taking over cities one by one, is the best way to achieve the Revolution.
These left wing billionaires will migrate to red states and support whacko activists once there.
Unless you have a new job or you are ready to retire, it is pretty tough to relocate. It is a bit easier if you are young and don't have a family to support. I have some young relatives who were able to escape Chicago and set up new lives elsewhere with working from home. They found new jobs when after bosses wanted them to return to the office..