If I had been in charge of California/had a sorcerer's hat to make magical things happen,
Disneyland would have opened in September and closed with this shutdown in December. The numbers were there, the OC was in Orange, I went to DtD for Labor Day and it ran so smoothly even with the crowds that was the least crowded I've felt DLR in awhile (the last several years my family/travelling party has been resigned to weekends/school breaks given our teens can't take much time away from their lasses, I really miss being able to travel to DL mid-week/non-holiday!).
Given that people have reported coming back from WDW positive here on this DIS, it is spreading at the parks and would happen here if DLR were open when the positivity rate was too high.