Not true. NYC itself could be protected for about $8B. The most expensive piece would be a surge barrier across Verazzano Narrows north of the bridge. The other two points east and west would be cheaper. The only catch is that extra storm surge deflected by the barriers would swamp NJ. But tough luck, Manhatten is worth more and costs more to rebuild.
I’m sure NJ would go for that. It might be easier to put stilts under all the buildings.