>>The alternative as they saw it was to upgrade their expensive Manhattan apartment or condo and to enroll their kid in an expensive private school.
Those that might have been thinking of enrolling their children in private schools can do so more affordably outside of NYC. As an example, most top tier private school base tuition in the city is around $55K/year/child (not including "suggested donations") while most great private schools outside of the city are sub-$30K/year/child.
>>I think I know one couple who stayed in the city and they were very well off.
Public school is an option too, as long as one can navigate the byzantine DOE processes. From a housing/apartment perspective, if more people flee the city then there is a delicate balance where prices may come down for families to once again find them more affordable.
I think I know one couple who stayed in the city and they were very well off.