Or should the current US Olympic qualifiers be grandfathered? An athlete's perfomances can differ from one year to the next. And each year brings new talent to the fore. If the goal is to send the best US team possible to Tokyo, doesn't that argue in favor of a new Olympic trials?
Recall that in 1968 there were two Olympic trials and that the second one, near Lake Tahoe, superseded the earlier one, in Los Angeles. The rationale was that athletes should demonstrate how well they could perform at altitude. So there is precedent for a trials to supersede an earlier one held for the same Olympics.