I noticed this morning that you can now click on dates on the calendar to begin the reservation process for 2021. You can even pick a resort and see prices. As of 7:15 central time, you cannot complete the process of adding tickets or checking out yet. The CM I spoke with yesterday told me that new packages for 2021 could be made starting sometime today. The info posted over the weekend states that BY June 28, new packages for 2021 could be made. Last night, there were no options to click on past December 2020. So, progress is being made towards reserving for 2021.
ETA: I just booked our 2021 package and reserved park days. Only resorts available right now are the ones scheduled to open still in 2020. Park hoppers available.