Know I'm a bit late into this thread, but I was lucky enough to be at both performances on closing day (I won the lotto for the matinee, and had bought a ticket in the last row of the mez for the actual closing). I also, thanks to the kindness of a very nice woman I met in line, got to go to the closing party.
So I can say for a fact that almost NOONE knew this was going to happen. The actors were totally taken by surprise (several already have other commitments), and my friend in the orchestra had no clue either. They kept it very hush-hush. And in fact, when they first started making comments that it wasn't closing, everyone laughed. We all thought it was a joke...
"Are you calling me a procrastibator?" Hunter, [title of show]
"Guess who's gonna get blamed for the war in Europe?" Eugene, Brighton Beach Memoirs