They followed the pandemic playbook and it's done now. The plan is to try to isolate and if that fails lock-downs and restrictions until the population is vaccinated according to health authority standards. That was 2 vaccines and shortly after everyone that wanted vaccines got vaccinated, federal restrictions started lifting. They might decide to amend the pandemic playbook for future plagues now that more data has been collected but that was the plan and that's what got done.

unless it's a variant so mutated that it's beyond the vaccines we got, I doubt there will be anymore federal restrictions.

I think they should just start requiring mask usage for anyone exhibiting flu or cold like symptoms anyway. Make it the norm for flights. I know if I got on a flight and saw a few people that were required to mask up, I'd mask up.