The suspension of the 2019-20 NBA season will affect the next season. With the league targeting a return on July 31, this season is expected to end as late as October. Because of this, the 2020-21 NBA season would start on Christmas.
A day which was used in the past to host special events and big games, will now become the opening day of the season, per Marc Stein of The New York Times:
If the N.B.A. can successfully complete the 2019-20 season under this structure, it is expected that the 2020 N.B.A. draft would be moved to October, with free agency to follow shortly thereafter and a tentative plan to establish Dec. 25 as opening day for the 2020-21 season.