Disregarding the fact that the International travel bans have not yet been lifted, if you try to book any 2020 Walt Disney World resort holiday either through a travel agent like TUI or direct with Disney, it comes up blank.
Disney have announced the following.
At this time, we are temporarily pausing new ticket sales and Disney Resort hotel reservations so we can focus on guests with existing tickets and reservations. Existing ticket holders and Annual Passholders will be able to make a theme park reservation before new tickets are sold; we will be reaching out to these guests soon to provide additional details. We will resume new sales of tickets and Disney Resort hotel reservations after that period of time. Theme park reservations will be limited due to attendance limitations and will be subject to availability.