With the advance notice of the impending snow storms on the East Coast US that could leave numerous 747's/777/380 snowbound in the US - and with advance notice of this cancellation (for what was a busy flight) I AM surprised that a 777/747 hasn't been taken off BOS/JFK to take on this single rotation. There was plenty of time to get a crew positioned out to HKG for the return segment.
I know this is simplistic to the extreme, but it looks as though there will be loads of planes and crews stranded in the US doing nothing this weekend anyway!