Winning New York City would be more than a symbolic victory for Obama. In New York State, twenty-three Congressional Districts have five delegates\ apiece, and six CDs have six delegates. Five of those six are in NYC. Were Obama to carry those districts, he'd score 4 delegates to Hillary's 2, or 3 to her 1 if Edwards tops 15%. In the remaining CDs, if Obama can just top 30%, the delegates will split 3-2 in favor of Hillary, or 2-2-1 if Edwards meets the threshold.
The point is this. Using the numbers in the poll you cite, and the conservative assumptions that Hillary wins every single district out of the city, that Obama everywhere garners at least 30%, and that Edwards doesn't meet the threshold anywhere, the pledged delegate tallies for New York State would be: Hillary 132, Obama 100. You can knock one delegate off of Hillary's total for every upstate CD in which Edwards cracks 15%; if he breaks that statewide, subtract another 6 from Hillary and 4 from Obama.
The point is this. Hillary's strategy is built on the assumption that she can leverage huge leads in NY, NJ, and CA to compensate for her losses in the south and midwest. And in the last week, that strategy has gone up in smoke. She's finished; if our national media wasn't innumerate, it would have noticed by now.