21 W 52nd Street is a NY landmark. If you got a reservation at 21 in its heyday, you might have spotted Al Jolson, Jack Kennedy, Judy Garland, Frank Sinatra, Papa Hemingway, Mickey Mantle, Marilyn Monroe or Steve Allen as they moved in and out of one of the many private areas. They were some of the many patrons recognized by the general public, but there were just as many regulars whose faces were unfamiliar, but whose bank accounts could support regular visits.
Like many institutions in the hospitality industry, it is unable to function profitably as a restaurant during the COVID crisis. Nobody can predict what will happen when the crisis ends. It may yet re-emerge.