I'm not much into politics, especially since I now live in Greece but I keep an eye on the more interesting stuff, and being a native of NY it will be interesting to see if NYC really does tank with the new democratic mayor.
This article explains why it might not happen any time soon.
The TLDR version is that Mamdani won't be able to keep most of his (questionble) election promises which would probably be devastating to NYC, because they are either impractical, delusional or not supported by other political figures who must lend their support in order for it to happen.
https://www.msn.com/en-us/travel/article/mamdani-starts-to-deflate/ar-AA1QClqm?ocid=hpmsn&cvid=691c29ffd5a94282a9f7a0a2349d675d&ei=8