Christilot Boylen retires at 73. Six times Olympian ('64, '68, '72, '76, '84, '92). Rather unfortunate for her that the only (non-boycotted) Olympics she missed in that period were the ones where Canada took a medal in team dressage.
While not anymore on the championship teams, she still competed internationally in recent years. Her last competition was right before the lockdown, in mid-March. She was born in Jakarta (then Djakarta).
Hiroshi Hoketsu is now (presumably) the only active athlete who is attempting to compete at both Tokyo 1964 and Tokyo 2020...