This. I'd be totally fine with a reschedule/voucher and would throw in extra to cover the delta in rates if they went up between my original booking and the day I want to redeem the voucher/credit.
I'm not so crazy about the idea of being willing to put up the delta money in the future.
Whilst a company keeping my money is unlikely to be investing my money in a growth account, the time value of money says to me, that I shouldn't have to fork over another couple of hundred for my rebooked trip, when it's force majeure.