Disney World's revenue has currently fallen by 100% this period. How much do you think the fair market value of Disney World should decline by? Clearly the answer is much less than 100%. Even if Disney World stays closed for two years, it's clearly a very valuable asset. As an asset it probably has a 50 year effective life, so 2 years of closing represents no more than a 4% loss in cash flow. Interest rates are essentially zero, so Disney World should be no more than 5-6% less valuable than it was before the pandemic.
The biggest risk for corporate assets isn't the direct impact of the lockdown. It's whether the experience leads to any permanent changes in people's behavior. If there's a permanent cultural shift where people stop going on vacation or visiting crowded amusement parks, then Disney World might be worth much less. But this is significantly more speculative than estimating the direct impact of the lockdown.