Preservationists worry board may seize on incident ‘to make the point that the whole thing needs to be shut down’Falling debris from a ceiling in the grand foyer of the John F Kennedy Center for the Performing Arts may have complicated a battle over renovations of the Washington DC arts center that could result in the building being demolished.A portion of the ceiling collapsed on Friday evening after heavy rain swept through the area, prompting officials to temporarily close the Edward Dure