In Denmark, most (all?) of the emergency measures have come with a sunset clause, typically a year from inception.
The risk is largely related to changing perceptions and standards for what is normal, beyond the pales & such. Once something has been done widely and publicly, it becomes more normal and less scary.
Deciding when the emergency is over is less straightforward than a fixed time period. A government that wanted to extend the measures indefinitely would just claim there's still an emergency.
And even if the emergency is not over in a year, it makes a lot of sense to reconsider if the measures (which were decided very quickly) are actually appropriate and necessary going forward. Hopefully a lot have been learned in a year.