If that is the case you can kiss WDW, Sea World, Bush Gardens, Universal good by forever. No company can weather being closed for 12 months with zero income.
You forget the backstop of the federal government. Disney would never be allowed to close forever. It is an American symbol. The government would take an equity stake, and set them up with their own printing press in the short term. Sea World, on the other hand.
Let's imagine, for a moment, that this was not a war against an invisible virus, but an actual war. I know Americans aren't used to envisioning bombs and tanks in US Cities, but it's not a theoretical impossibility to imagine a scenario where a Blitz campaign was being run over Southern California, and ground fighting in Florida. In the event, of an actual ground war in the US, we would reasonably expect that all places of amusement in areas with active fighting would be closed indefinitely, and we know that wars last YEARS. We wouldn't be able to comfort ourselves with the idea that these places can't stay closed for a year for financial reasons, we would have to tell ourselves that they are simply going to be closed, and we're going to have to learn how to deal with it. If Disneyland Paris was around in 1940, it would not be open, and all the financial arguments of how they couldn't afford to stay closed would fall on deaf ears because of the situation on the ground.
The question becomes is actual war an analog for a pandemic? At least in terms of determining if it's safe for businesses to operate if effective social distancing is difficult.
Then there is the cost. I'm highly suspicious that there can be a set of standards that can both provide adequate safety for cast and guests, and be financially viable. Disney may be brainstorming possible solutions, but IMO, once they run their numbers it will be too expensive to operate, for the number of guests they will be able to serve (or maybe even attract). The fallback position would be to work in conjunction with local, state, and federal governments to ensure the business does not go under.
We are a country where Mickey Mouse affected copyright law. Mickey Mouse will get his own personal bailout.