The former World Cup gold medallist is taking an "indefinite break" from the sport.
The Kiwi single sculls supremo will seek his third straight gold medal in 12 months.
The 1988 single sculls bronze medallist had been battling cancer.
The world recordholder beat the two-time Olympic champ by eight seconds.
The former single sculler is now focused on a men's double bid at the Tokyo Olympics.
The 41-year-old master has replaced younger rival Robbie Manson in the NZ boat.
A new selection policy will help the two-time gold medallist.
Kerri Gowler and Grace Prendergast are hunting two golds at Tokyo.