Retired school principal Elizabeth Mulvihill moved from Long Island to South Williamsburg a couple years ago because she's old and doesn't want to drive anymore. So she dropped $1,040,000 on a two-bedroom apartment in Schaefer Landing, a development on the East River that opened in 2006. At first life was grand, with the New York Water Taxi whisking her away to Manhattan for doctor appointments in 15 minutes. But then the boats stopped running in......