I'm going to weigh in here from a medical standpoint (as an in-the-crap-for-the-past-year Covid med professional). I'm going in Nov 2021 and have a pretty optimistic outlook for a good portion of "normal" Disney returning by then.
It is incredibly likely that we will see Covid restrictions lifted by the end of the summer around the country. Everyone who wants a vaccine will have been able to get one by that point. As soon as the CDC officially updates their recommendations, we will see businesses start getting rid of their restrictions because there is no longer a legal obligation. Whether or not Disney follows suit, we will see. They know that they need to start making up for a year of financial loss and they know that a lot of people aren't coming because of the restrictions. So who knows.
As soon as vaccines are available for everyone 16 and up, it is no longer the responsibility of public health to protect people. It becomes personal responsibility. We see this each year with the flu. Yes, the flu is different. But if you don't get your flu shot and you get the flu, who's fault is that. Sure you may get your shot and still get the flu, but it won't be as bad as if you hadn't gotten it. This is the same thing with Covid. Data is showing wonderful results for vaccinated people not contracting it and those that did had mostly mild symptoms.
What does this mean for Disney? For the majority of the parks, you are outside. Yes, there are ride queues, shops, and restaurants, but data shows that's not really how this is spread. It is spread in close-contact smaller groups. Not outside, not short & quick interactions. So I wouldn't be surprised to see Disney change their policy to being "Masks recommended but not required". This would make those who are comforted from mask wearing feel like they are still able to make the personal choice to mask when needed and those who want to not wear masks happy to spend their money there.
Someone mentioned something about not having herd immunity because the kids won't be vaccinated. First, there will never be total herd immunity because this is going to be around just like the flu and there are a lot (about 30% was the last poll I saw) choosing not to vaccinate. Also there is plenty of data to show that children do not transmit the virus as much as adults. There are clinical trials going on with kids 6 and up, with 6 mos to 5 yrs currently in the works (my daughter is enrolled for the trial should it start). They are looking to start vaccinating kids by the beginning of next year. So vaccines for kiddos isn't far off, but it won't be the determining factor is business getting back to normal. Except schools, where most are saying that are at least going to still have masking in the classrooms.
Anyway, just a thought.