Both the flagship NISMO and NDDP/B-Max teams will retain unchanged line-ups for 2021.
Ronnie Quintarelli - now Nissan's only international GT500 driver - will stay alongside Tsugio Matsuda for an eighth consecutive season in NISMO's #23 car, while Kohei Hirate and Katsumasa Chiyo get a second season together in the #3 NDDP/B-Max machine.
Kiyoto Fujinami had been tipped for a promotion to Nissan's GT500 line-up after his championship win in GT300 last year alongside Joao Paulo de Oliveira, but will have to wait at least one more season for his top-class graduation.
Fujinami was one of four drivers Nissan tried out in a driver audition last month at Fuji Speedway along with Matsushita, Keishi Ishikawa and Hironobu Yasuda.
Takao Katagiri, the president of Nissan's sporting arm NISMO, said: "This year, we have welcomed Matsushita to Team Impul. Together with Hiramine, we expect him to take Nissan to the next level and create a sensation in the Japanese motorsport world.
"We are currently preparing and developing the Nissan GT-R NISMO GT500 to make it even more competitive. This season, all of us at NISMO, including the team directors, drivers, team staff, and development team, will do our utmost to show the fans exciting racing that only the GT-R can deliver."
Mardenborough losing his GT500 seat throws into doubt a tenure in SUPER GT that began in 2016 following a single season as part of Nissan's ill-fated NISMO GT-R LMP1 project.
Jann Mardenborough, Rookie Test Driver for Nissan e.Dams
That year, he contested the GT300 class and partnered Kazuki Hoshino in a B-Max Racing-run Nissan GT-R NISMO GT3, winning only his second race in the category and ended the year fourth overall, before stepping up to the GT500 ranks in 2017.
In two seasons with Impul, Mardenborough scored a single podium finish alongside Sasaki before being moved to Kondo to join Takaboshi. In two seasons together, the best result they achieved was fourth place at Buriram in 2019.
In addition to losing his SUPER GT drive, it's unlikely Mardenborough will continue to have a role in Nissan’s Formula E project, in which he has served as a simulator driver. Takaboshi meanwhile is set to continue as test and reserve driver.
Nissan will announce its full worldwide motorsport programme for 2021 in February.