This is from today's MP DLR Update (6/08/20):
From GAT (referring to the WDW reservation system for reopening):
"While we still don't have an opening date for the Disneyland Resort, we imagine they will implement a similar reservations system. Once an opening date is announced, guests may not be able to book a new reservation or tickets for a period of time. Because of this, we are highly encouraging anyone who is interested in visiting the Disneyland Resort this year, to book as soon as possible.
We are recommending that our guests rebook for dates during two of our favorite times of the year: Halloween Time or Holidays at the Disneyland Resort. Additionally, if your readers are more comfortable traveling next year, we are accepting new reservations throughout 2021 as well."
Nothing was said in today's DLR Update about Disney closing the DLR on site reservation books today.