Harimoto will no doubt be the 1st singles, unless he dies in an accident or becomes gravely ill, the latter of which happened to
Rikako Ikee.
Mizutani has said he has only a 50% chance making the singles. Niwa also knows the risk of dropping out if he doesn't make the singles. For the 3rd spot, it depends how "adventurous" the JNT feels, as in how much they want the gold medal. The circumstances are much more dire compared to Rio. As it stands, I'd say they don't even have a realistic shot at podium. Harimoto is too volatile, with a high standard deviation. Niwa is either free-flowing or free-falling. Mizutani is surprisingly consistent given his eye condition, but like he said after the All-Japan Championships, his stamina can't really keep up anymore.
Because of the XD, Yoshimura does have a realistic chance, especially if Ishikawa makes the team.