Sure there is, there could be new variants that the vaccines don't protect against. The criteria for the various levels of reopening were set at the beginning. Those are what should determine the reopening according to public health experts.

The vaccines have proven highly effective at protecting against COVID and its highly transmissible variants, and it's unlikely that we'll see a new variant arise that exhibits sufficient immune escape to result in severe infections in vaccinated people.

The criteria for the various levels of reopening at the beginning were due the need to protect vulnerable people who did not have the opportunity to magically protect themselves by getting vaccinated.

Surely you understand there are more considerations than just what public health experts say right? They are a part of the answer, not the whole.