Just a thought. If we are unable to go to Disney as per our reservation because we are unable to fly due to the restrictions, which are out of our control, Disney may, and I stress may, offer the 35% discount on a similar reservation for next year. I'm not modifying or cancelling my trip until it is absolutely necessary because if they do this as a goodwill gesture they may only do it for existing 2020 reservations and if you cancelled or modified then tough.
The way I feel is that there is nothing to lose if you are happy to go next year like I am, even if I pay the balance when due that'll be taken off next years reservation even at full price. I don't even regard it as a gamble.