A lot will depend on which version of Niwa shows up... if they still decide to put him out there in 2021, which I expect they will. Keep in mind that any home-field advantage (I think this is overblown) may be nullified if there are limited spectators in 2021.
My opinion is Japanese shouldn't have re-assurred same team selected for Tokyo 2020 would still be the same for delayed 2021 games, lots can happen 12 months down the track. I like the look of Uda and Hina Hayata and if still progress the rate they have been could make a case to replace existing members. I think CNT will see some potential 2020 inclusions be left out.
I'd hate to imagine a games with limited spectators. Strange concept.