From their website: "In the event your flight is canceled, you may request a refund of your unused ticket to the original form of payment."
I know they are good with no change fees, but one easy way to help out here would be for them to make all tickets this week fully refundable, regardless of whether the flight operates. This lets those who need to be somewhere to book an alternate flight and if their original flight actually operates, it's one more seat for the hundreds of thousands of stranded pax.