Any one of the few who have any information on this will not be posting it here ... so your guess is as good as any.
When we booked July they were required, when we got there they were not. When we booked November they were not required, when we got there they were. Just be prepared for anything.
And note: mandates are to protect Cast Members, maintaining staffing and save insurance. I'm sure Disney is working closely with their lawyers, current CDC guidelines and once they are comfortable with it ... we will know shortly thereafter.