“A month after the Dia Art Foundation scrapped its plans to open a museum at the entrance to the High Line, the abandoned elevated railway line that the city is transforming into a public park, the Whitney Museum of American Art has signed on to take its place and build a satellite institution of its own downtown. … Plans call for the new museum to be at least twice the size of the Whitney’s home on Madison Avenue at 75th Street,” museum officials said, “and to be finished within the next five years.” Renzo Piano, architect for the Whitney’s now-abandoned uptown addition project, will design the new museum.