My guess would be Disney knows exactly what they are doing. I would venture into speculating they probably want two steady weeks of declining numbers in both cases and deaths in the state of Florida. They probably want more testing as well and may even have a set number of tests per day. This is of course if they open up to state residence first as CDC is still discouraging non essential travel at this time. Disney will not go against CDC recommendations. Because of this I speculate a small number of resorts opening or each resort will only operate at a third of the capacity, increasing capacity each week if cases/deaths continue to decrease.
When the CDC removes its travel recommendations they can start allowing domestic travel in small numbers. (Assuming they only start with state residence.)
While Disney is waiting on those criteria to be met, the real headache comes at operations and logistics. How many resorts to open. How many rooms at each resort to open. How many buses/boats are needed. Reduced transportation capacity and scheduling. Etc. Etc. And putting all these measures in motion with current reservations in place. It won't bode well. WDW is most likely opening up in phases. Even when they set a date to reopen, some current reservations will still need to be altered.
This is going to be a very tricky year for many, many reasons. And if cases/deaths start dramatically increasing again, there is no doubt they will pull the plug on everything again, much quicker than they did initially.