I generally dislike referenda. It usually results in bad law.
Nevertheless, theoretically a state referendum on withdrawal from or division of the old state of New York could be sold to the public in a way that secures the assistance of the masses in the large population centers - and thereby turning demographic obstacles into demographic advantages.
Example Proposed Referendum:
Vote YES or NO
The boundaries of the State of New York shall henceforth consist of the five boroughs of New York City and such and such counties [add whatever areas seem most feasible, be sure to include areas with a great number of affluent (RICH) people]. All public revenues generated from these areas shall remain with the State of New York for the benefit and general welfare of the residents the State of New York. Areas outside the newly defined boundaries of the State of New York are henceforth to be known as the State of Amsterdam.
The voting portion of the FSA in the large population centers should be eager to get rid of Amsterdam. More of the public treasure/lucre would be available to them. Get it?
EDIT:
Article IV, Section. 3, Clause 1 of the United States Constitutions reads: New States may be admitted by the Congress into this Union; but no new States shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress.