Nothing is free. NY will raise their taxes to pay for it.
Let me see if my math is right. $10,000 per year per in-state student. About $160,000,000 to fund the program.
That takes care of about 16,000 students, the size of a mid size state university. One should figure on a much larger number. Also, free tuition for now, free room, board, books, fees, and spending money within two to three years.