Here's the story:
Goldman bought the site in 2007 years ago, says Crain's, and planned to build a luxury hotel there, because that's what was happening in Williamsburg at the time. But after the recession hit, they struggled to get the project financed; finally, they brought in L+M, an experienced low-income housing developer, and designed the project, which will be financed in large part by subsidies, tax breaks, and especially bonds issued by the city's Housing Development Corp, designed to facilitate new affordable-housing development.
Additionally, the retail space on the ground floor will be mostly given over to an as-yet-unnamed supermarket, brought in through NYC's city's Food Retail Expansion to Support Health (FRESH), "an effort to bring healthy supermarkets to underserved areas".
So, city-incentived mixed-income development and socially responsible businesses. It's almost as if the government isn't actually the enemy.