In Trump's original 1987 proposal for the site, the southern part of the railyard was to become Television City, a production facility which would also include a new headquarters for NBC. My understanding is that when the studio component was removed from the project that became Riverside South, the fate of the southern part of the railyard was left undefined. However, something big, expensive and temporal will likely get built here at some point.
Just to the south of the railyard is the power plant for the IRT subway system.
Immediately to the southast of the railyard is the former Sheffield Dairy which had a direct rail connection to the yard. The dairy was later converted to studios for CBS-TV.
When I last visited in the Fall of 2007, 59th Street on the southern edge of the old railyard was still home to some rugged old survivors from the past. Also, one of the few desolate streets in Manhattan where tour buses can park while waiting for their contents to leave their cash on the island. Not sure what the ultimate plan for this area is.