Miyazaki is kind of being the boss at JTTA for deciding the team, although he said all coaches opinions will be considered.
Regarding women's team, indeed he said that the team will be built to beat China (meaning they are optimistic they can win other teams easily - which i think is the case). 2nd seed is guaranteed even without Hirano. He said they are basically facing 3 choices: (1) Ito to play 2 singles, choose a right handed player to team up with Ishikawa for doubles, and the logical choice is Hirano (2) choose Ishikawa as an ace to play 2 singles, and then choose a left handed player - Hayata - to play doubles with Ito (3) choose Sato to play 2 singles and let Ito play doubles with Ishikawa.
Regarding Men's team, the ambitions are more modest, they want to build a team to get a medal [meaning they are being realistic about their chances of challenging China]. For that purpose, it is important to stay seeded #2, which is possible only if Mizutani is being selected. We know from the man himself he is not very motivated to play at the Olympics, but he will do his job for the country. Miyazaki then said that if the 2nd was guaranteed actually it would make sense to let play the right-handed Yoshimura with Niwa in doubles and let Harimoto play 2 singles - instead of selecting Mizutani.
And yes, they will decide on January 6th. I don't know the reason but they are committing to that date.
He finally praised Ito, and said often her matches against Chinese players are often decided by a narrow margin, its often just the question of being a bit more lucky on a net or edge
