was open to arrivals on a runway Concorde could use, I would think the weather at the alternate airports would put a stop to any chance of flying the service. Even if you did fill the aircraft right up, it would simply not be worth taking any risk what so ever setting out to an unknown situation, hence why the subsonics got cancelled too.
With so little aircraft in the fleet, maybe 3 or 4 at each airline flying (with the others in schedule checks) the last thing they would want to do is have aircraft positioned in the wrong places, causing further cancellations and customer inconvenience.
had flow out today they would have had 2 a/c at JFK
and maybe only 1 serviceable in Paris.
I'm sure the engineering staff will be rubbing their hand with the cancellations, time to catch up on the more mundane tasks with out an a/c to prepare/depart.