There is plan to add to the housing stock as well: https://www.nyc.gov/mayors-office/news/2026/05/mayor-mamdani...
He is also aggressively going after landlords withholding repairs, maintaining dilapidated units, etc. and thus tackling the quality of the housing stock problem.
So he'll move to a higher office and leave his messes for the next sucker.
Also outcomes are generally not positive or negative in & of themselves: if you could specify who exactly you anticipate will be worse off, it would make your comment much more insightful.
Secondly... the track record of NYC mayors' post-mayoral careers is abysmal. Not one mayor appears to have successfully held elected office after their mayorship. There's one failed bid for NY governor (unexpected primary loss to the senior Cuomo), and four failed bids for president, the most successful of which being Bloomberg's 4th place showing in the 2020 Democratic primary. So as a springboard to higher office, NYC mayor is absolute garbage.