After a Monday article about how the middle-class Harlem housing complex Riverton Houses' owners might default on their loan, the NY Times now looks other big real estate deal that might go sour. Like the Riverton Houses, Stuyvesant Town was bought by a big real estate company who hoped to convert more rent-stabilized units to market rates and make a profit (but it's been slow-going so far). And there are other possible victims, like Harlem's......