What happens if The Grand Calcutron leaves the battlefield after players hand cards have already become programs?
Mark Rosewater, the Un-set rules manager, has answered this question directly:

What happens to a program without the Grand Calcutron? Does it returns to hand? Can I play cards from it? Do I still need to follow the order?
If The Grand Calcutron every leaves play, the cards in the program return to your hand.