Saying they won’t prosecute the charge. There are some foreign jurisdictions that still make it a crime to patronize one, while its not a crime to engage in the selling. It will be interesting to see if the same kind of enforcement occurs in New York or if it will simply stop entirely.
What usually happens over time is that once the practices start occurring, it begins to spread from there. Obvious examples are no fault divorce and marijuana legalization, but there are plenty of other examples.