I have my own idea around this.
One of the differences I've noticed about New York compared to Sydney is the amount of fallow or under utilised space in New York.
Either buildings are left un-renovated and decrepit or are operating as a single level retail or renovated and in good condition but unlived in.
In Sydney especially as close to the CBD as we live here on 120th st pretty much 90% of the buildings have been renovated or maximum utilisation which is why we have have great suburbs as this is the natural expansion out.
In New York slum landlords counting on capital growth are happy to just let their buildings waste away until they hit 'the big payday' and sell out. In the mean time however both quality of life is lower and taxes go unrealised.
The other issue is that people keep an apartment in the city but they claim it as their second residence so that they dont have to pay income taxes as a NY resident. Now I dont care if you are or aren't fudging your taxes, I just mean you spend a substantial amount of time outside of the city and therefore dont bring revenue into the city through living here (eg. groceries, restaurants, sales tax etc)
So my proposal is this;
"If you own a property in New York BUT you claim it as your secondary residence eg. your home in CT or The Hamptons is your primary home" then you have to pay a factor of 2 x normal property taxes.
"If you own a property in New York BUT the building is abandoned and not operational then you have to pay a factor of 3 x normal property taxes.
This will take care of abandoned or under utilised buildings pretty quickly.