Disney Wolrd have released information on how their reservations system will work for parks.
The Disney Park Pass System will operate via disneyworld.com. To use it you will need a valid park ticket or annual pass and access to the My Disney Experience app.
You need to link all the above together to be shown a calendar of dates where you can select your reservation slot for your chosen park. Park hopping will not be an option during the reopening, if you already paid for it you will be refunded. Park hopping will be available if you purchase a 2021 ticket. You must make a reservation for EVERY DAY you plan to visit a park. Families may link their passes together.
Disney will be in contact with ticket and pass holders to advise when they can make a reservation.
Disney also announced thay by June 28th hotel and ticket options for 2021 will become available. So be sure to act fast as we would assume there will be reduced availability compared to normal.
News from Disney Worlds reopening plans is coming thick and fast. It sounds like they are about ready to reopen the gates. It remains to be seen when park hopping will be allowed, if at all in 2020.
News: Orlando Sentinel