Or you say “until further notice”.
Indeterminate end dates are not a new problem.
They don't have a mechanism for doing that. A military base near me has had continuous flight restrictions for decades. Each notice lasts a few months (e.g. https://tfr.faa.gov/tfr3/?page=detail_5_8746) and before it expires they issue a new one.
Can you imagine how much more wild the speculation would have been if they had said that instead?
FAA restrictions aren’t applied in a hand wavy fashion.