NJPW announced last night via Twitter that Wrestle Dynasty, originally scheduled for August 22nd, 2020, has been postponed to a date to be announced in 2021:
In the interests of running the best and safest possible event for fans, NJPW has arrived at the decision to postpone Wrestle Dynasty in Madison Square Garden.
Sorry for the delay, but we'll be back stronger in 2021!
— NJPW Global (@njpwglobal) May 7, 2020
This is due to the uncertainty of COVID-19 and the impact that may still be felt in August, especially in the New York City area. Fans can sign up to be notified the moment the new date is announced by going to this link.